So far, opinions have been expressed in the literature that the Nematodes are mainly parasitic, of which a small part is free-living and mostly lives in decaying substances. 4 SMITHSONIAN MISCELLANEOUS COLLECTIONS CONT.89 In the collections of the parasitic species today there are no more than 20 to 30 percent new species. Comparison of the number of genera would not give an adequate conception due to the lack of uniformity in the classifications of different workers.
But throughout the parasitic nematodes it is always the same unicellular skin gland as it is in the free-living forms, as was shown 30 years ago by Jaegerskioeldi and Golovin.
10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 KEY TO SUBFAMILIES OF ENOPLIDAE
The chitinous rings surrounding the jaws probably correspond to the cephalic capsule; the outer chitinization of the head, the "cephalic armor", corresponds to the inner layer of the reduplicated head cuticle in Leptosomatinae. In Enoplolaimus (Fig. 7) the jaws are weak, each in the form of two parallel, chitinous rods connected anteriorly and provided with two hooks spreading laterally; between the bars of the jaws there is true onchi, which spreads inside the oral capsule (cf. In Oxystomina (fig. 8) the amphid is very distant from the anterior end and becomes very elongated, with a large anterior opening, the opposite of the common condition.
Halalaimiis (fig.9) represents a further step in the elongation of amphids, so that the primitive pocket form could hardly be recognized without the intermediate Oxystomina.
14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 Subfamily Mononchinae
Some doubts about their place in the Enoplatar arise from the shape of the amphids, which do not have the typical bag shape, but are spiral or round (fig. i8). In the genus Halanonchus, whose themes have the same typical features, the amphids are almost of the pocket type (Fig. 19), which makes the interpretation of the shape of the others very likely as being of the modified pocket type. The tail of the male (Fig. 25) with its numerous pre-anal papillae also corresponds in general terms to that of the Dorylaimidae.
It is the only member of the order with a more or less extensive connection of the esophagogustocuticle; this is probably due to the reduction of the musculature in the front part of the former.
20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 The Plectidae are mostly terrestrial or fresh-water nematodes
22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
Synonchium (Figs. 39-40) has three of them, quite in Enoplus, butitis, of course, nothing but a very clear case of convergence, no other character is. All have only four cephalic setae and almost all a bulb and preanal papillae, providing good diagnostic characters for different species. The amphid in some forms is a typical small spiral that lies very far forward (Fig. 42), in others the shortening of the head shortens the spiral, which thus becomes the slit-like amphid typical of these other genera (Fig. 43).
The Monoposthiinae are characterized by a peculiar cuticle with longitudinal rows of spines, in some forms fused into continuous wings (fig. 45). The most striking feature is the general shape of the body with the swollen esophageal portion commonly called the 'head' followed by the thin 'neck'. fig. 47, 48), but the same form of body, although not so well developed, is found in several members of the Desmodorinae. 24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL.89coarse, distinct striations of the cuticle, coarser behind the head, is a.Coarse, distinct striations of the cuticle, coarser behind the head, are a.
Steiner (1926) proposes to treat the Epsilonematidae (Fig. 47) with the fixed adhesive bristles, separately from the Draconematidae, the tubular bristles each being connected to a gland which is probably a cement gland. They look like body segments and have led to comparison of these forms with the annelids, but they are purely external or even secreted and have no relation to the internal organs (fig.). Also interesting is the habit of retaining the eggs on the outside of the female body.
Under this name all true free-living forms are united with the straight (unreflected) ovaries (fig. 51). Despite the morphological characteristics of the group, there are very gradual transitions between the different members, so that it appears to be a very natural whole.
26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 Subfamily Comesominae
The cuticle was never so coarsely striated as in many members of the Monhysteridae; it is always very soft and pliable, mostly with a very fine streak or plain. The most characteristic features are the spicules, strongly curved and accompanied by a double retrograde gubernaculum (fig. 56). In the Axonolaiminae, the amphids usually have the shape of a bent horseshoe, an elongated oval, or are rounded (fig. 59); it is likely that this form would be considered more primitive, even than the spiral form.
28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
In the esophagus softens a bulb with the masticatory apparatus inside; a preneurial swelling is present in some forms (fig. 61); others become a second true bulb, usually called the middle bulb, the posterior cardiac bulb reduced to other muscles (figure65); posterior bulb, only the glandular cells are preserved, the only muscular bulb is the anterior. In Aphelenchus and some other genera, the cells of the posterior part of the esophageal brain are not separated by the intestinal constriction, so that it appears as if the nerve ring is located around the anterior part of the intestine. There appears to be no group in the families previously discussed, for which the organization of this order could be closely compared with good reasoning.
30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 Subfamily Cephalobinae
It is likely that the main plate of Anguillulinae is isohomologous to only one plate of Cephalobinae; therefore, the oral capsules of both are not homologous to each other. All are moss-dwelling species with two rows of remarkable, asymmetric, cuticular growths on one side of the body, which thus physiologically become the ventral sides, or other differentiations of the epidermis, often of a very unusual appearance, and with cephalic growths (Fig. 66). 32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL.89 family as free-living genera, because of the great resemblance of the family as free-living genera, because of the great resemblance of their free-living bisexual generation to free-living forms.
The free-living generation has the typical rhabditoid esophagus like other free-living forms; the parasite generation has a simpler esophagus without swellings or bulbs, muscular throughout its length. Body with typical nematode-like appearance in free-living forms, swollen in the females of some plant-parasitic species, but without enlarged cell interior. In most of the members of the Tylenchinae, as well as in the Diplogasterinae, the posterior part of the esophagus is connected, and the border between and the intestine is easily seen.
Aphelenchus, the esophagus is subject to further evolution, the esophageal glands no longer come into direct communication with the body of the esophagus, the tubular part becomes narrow and the connection with the intestine cannot be easily observed; sometimes that part of the esophageal tube becomes short and the beginning of the intestine is very close to the nerve ring. The ancient genus Diplogaster, which until now united almost all species of the subfamily, must be divided into several independent genera that are very clearly characterized. The earthworm parasite, Ungella, should apparently be placed here; the hook-like chia may be considered homologous to the teeth of Diplogaster, and the preneural sofageal swelling is well developed, but there does not appear to be a sharp division between the two parts of the esophagus, as in typical members of the Diplogasterinae.
A systematic conclusion from these very real similarities could only resemble that arrived at under analogous circumstances by the carcinologists placing the aberrant Rhizocephalain order Cirripedia, and similarly the parasitic copepods with the free-living forms in the Copepoda. Steiner (1923) described a parasite from a sawfly larva and, because of its general similarity, referred it to the oxyurid genus Aplectana with all its other species of intestinal parasites of Am-. It is now referred to a separate genus, Steincr- nema.) The author found a very closely allied species, probably allied to Steiner's, in acutworm, fortunately accompanied by their larvae, which proved to be typically rhabditoid; the influence of parasitism can also produce very similar results in both ranges, i.e.
38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
The main ground for separation from the last is the presence of the intestinal caecum in Cruzia, but it is safer to take the taxonomic characters from the more constant mouthparts and male genitalia than from the parts of intestine which are variable in many closely related groups. Oniscicola and Cmznema, with a typical development of the esophagus, may be included directly in the Kathlaniinae. BulhoesiaSchwenck, 1926);LeidynemaSchwenck, 1929; Severianoia Schwenck, 1926; Cephalobellus Cobb. i) Males with agubernaculum Syphaciinae Here are united most of the known monospicule forms of the Oxyurata, with numerous genera and species in both vertebrates and invertebrates.
A further division as proposed by Walton (1929) and Travassos (1930) would be difficult to follow without a more complete treatment of the subject. Free-living stages of Strongylidae have been preserved as evidence of their true nature; it is probable that, owing to the semi-saprozoic life of the Oxyurata, they retained traces of a typical resemblance to the Anguillulata. But other parasitic orders have no free-living stages, and are more specialized in their parasitic life.* Thus little may be said of their relations.
But the wisest course at the moment would be to keep all three separate, as Yorke and Maplestone have done.
CONCLUSION
NO.6 CLASSIFICATION OF NEMATODES FILIPJEV 4I Linne, i.e. the registration of similarities and differences, only slightly and superficially colored by the theory of evolution. The absence or presence of a distinctive character should not result from the exclusion of a particular form from a group when other characters are similar.
LITERATURE CITED^
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
Contributions to the Science of Nematology, 4, p. i) Segmentation of their organs illustrated by three new free-living marine genera, (2) color reactions of intra-vitam, (3) nema population on beach sand, (4) location terms for cytology descent and (5) functions of amphids.
44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
A remarkable new mermitid, Tetramermis vivipara. sp., from the feces of a guinea pig. Oxyuridae), a newnemic parasite of the Japanese beetle (Poppiliajaponica Newm.).
56 SMITHSONIAN MISCELLANFOUS COLLECTIONS VOL. 89
58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89
EXPLANATION OF PLATES
Symplocostoma ponticum Filipjev, showing an oral capsule very similar to that of Eurystomina; in addition to the main onchy or spear, there is a little leading onchy on its side; part of the floor of the oral capsule has become isolated and forms a cuticular "lens". According to Philip, 1918. Trilobus brevisetosus (W. Schneider), showing a large oral capsule followed by a posterior chamber with two small denticles inside; there is no "circumoral pocket".
60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 89 Order CHROMADORATA
Odontonemaguido-schneideriFilipjev, a representative of the Chromadorinae, with a small spiral placed far forward; the large tooth of the oral capsule is characteristic of some generations. Metachromadoramacroutera Filipjev; Simple strong cuticle rings are characteristic of all Desmodorinae, but the distinct head stria only in some of them. Monoposthia mielcki Steiner; simple rings of mono-poshiinae interrupted by rows of ridged longitudinal spines; a desmodoroid parallel to Richtersia; notice the roundel.
Ceramonemaannidata (Filipjev); the four longitudinal crests of the cuticle are like those of the Monoposthiinae; the much reduced mouth structure and the horseshoe-shaped amphid resemble those of the Draconematinae; the large rings of the cuticle are very characteristic. Note the peculiar shape of the body with its "neck" and the adhesive non-tubular set in the middle of the body. The chitinous ring of the oral capsule becomes very large and gives way to a spacious oral capsule inside; the rods in the v^ralles of the vestibulum are better developed.
Note the thin cuticle, the poorly developed chitinous ring of the oral capsule, and the round, thick-walled steam hyd, or what may be called a spiral whorl. The vestibulum and the oral capsule are strongly developed; both branches of the horseshoe-shaped amphid are closely pressed together. Note the remains of the preneural bulb, characteristic of the Anguillulata; in other species of the genus there are no more hints of it in the zygonic generation, but it is always very distinct in the bisexual one.
