Peristomium fused with prostomium and the anterior part of the latter largely hidden between its forward-directed para-. Notocirrusarisingjustdorsad (mediad) and slightly caudad of the notopodial setae, rather short, simple, tapering and reaching slightly beyond the midline. 7, 8), usually twelve pairs on each side of middle segments, but somewhat less towards the ends of the body.
Towards the ends of the body similar modifications occur to those affecting the notosetae (PI. XV, fig. 6). Nuchal whorls similar to cephalic tentacles but thinner, reaching to or near cephalic margin of prostoma. The hard, white chewing plates of the mandibles, in addition to the large lateral tooth, bear three small teeth near the midline.
The basal part of the neurocirri is much reduced, leaving only the short, bluntly rounded cirrus that reaches the end of the acicular process.
ONUPHID^
Except for a small brown spot at the base of each notocirrus and a smaller one at the bases of the tentacles, the specimens are colorless. Probably the styles of none of the dorsal tentacles are quite complete, the tips of all being more or less frayed and clipped. Delicate color lespectinate setae (PI. XVI, fig. 47) occur between the bases of the dorsal limbate setae from III to the caudal side and form a dense group, except on the first two or three parapodia.
Neurocirrus arises near the base of the ventral surface and has a similar shape and almost the same length as the postsetal cirrus. From the ventral level of the first they gradually rise until the dorsal level is reached by the eighth. At L (fig. 60) it is a small blunt papilla, ventrocaudad to the tuft of seta, and further posteriorly it disappears altogether.
On the fourth foot (V) those in the almost dorsal part of the fascicle are replaced by simple acute setae, but.
272 PROCEEDINGS OF
XVIII, fig. 77) large and prominent, the undivided body alone of the first three exceeds half the width of their segments, somewhat protruding from the anterior ventrolateral region of their segments. They arise on the dorsal side of the base of the parapodia by a stout base, on the ventral or lateral side of which the neurocirrus is borne (PI. Several anterior pairs are very large, the second in all cases exceeding all the others and when all the way to the tip of the notocirrus on the opposite side, the first being about seven-eighths and the third about three-fourths or.
This spiral arrangement of the gills continues to at least XXXV, the number of turns varying with the length of the gill, the second and longest having twelve. Neuropodial acicles three or four, narrow, curved, terminating in acute tips projecting beyond end of acicular process. Set of first four parapodia (II-V) mostly with compound hooks (PI. XVIII, 79 and 80) arranged in a vertical vertical series of about six or eight, of which one, much stronger than the others , it is.
Color generally faded to a dull gray, the front slightly purple and purple zones on the cephalic tentacles and spots at the base of the neck cirri. Both notocirri and neurocirri are simple, conical styles without differentiated sirophore and of similar shape and size, not quite reaching the terminal end. lips, the neurocirrus arises on the antero-ventral part of the base of the neuropodium near the side of the mouth, the notocirrus almost halfway out on the postero-dorsal aspect of the foot. It continues to decrease, shifts to a more ventral position and finally disappears, leaving only the short, broadly rounded pre-setal lip of the low, flat parapodia of middle segments (fig. 88).
They have the usual structure, being coarse filaments containing a large axial blood-vessel, and within the limits of the piece show no signs of being flattened. Chewing plates white and hard, slender, ovate, with smooth or slightly wavy edges, borne in a distal depression of the stalk, projecting beyond the chewing plate on the lateral side like a blunt tooth. The mandibles of the type are much larger than the cotype, although the two worms differ but only slightly in size.
Although transparent and almost free from incrustations, the character of the valves cannot be determined. The first (PI.XVIII, fig. 97) have terminal teeth which continue almost in the direction of the stem and are not set at a considerable angle as in most forms.
LUMBRINERID^
From the point of greatest diameter, about XXX, the body tapers very regularly and gently towards the caudal end, being strictly conical for most of its length. The first few are very small, slightly compressed tubercles with an obsolete anterior lip and a subfoliaceous, cuneate-oval postsetal lip as long as the body of the foot (PI. XIX, fig. 101). Mandibles (PI.
Immediately behind them and in front of the lip is a small fold that protects the end of the mandible. At the end of the part, the parapodia (fig. 113) are thinner and narrower into simple blunt points. On the other hand, their possession of a nuchal papilla distinguishes them from most species of both sexes.
The main peculiarity is found in the remarkable elongation of the postsetal lip of the middle and posterior parapodia, which is rather pronounced as in L. The shape of these brackets differs. somewhat different from that of Japanese examples of the species. Neuropodia slightly thickened distally, divided at the tip into a very short presetal lobe and a longer, stiffly projecting postsetal lobe, approximately equal to the body of the neuropodia.
Form slender, subdued, but due to the prominence of the parapodia appearing enlarged and depressed in the middle and posterior regions. On the anterior parapodia, the edges of the setae are smooth or nearly so (fig. 146); farther these accounts become more prominent, especially the ondorsaletae, which. Anteriorly (fig. 150) they are nearly as long as the segments, but gradually become smaller at the same time as the segments lengthen until they are only one-third the length, though near the caudal they are again comparatively longer.
All specimens are stout and more or less inflated anteriorly in the proboscidial region and taper rather abruptly to a thin and attenuate posterior portion. Remainder of body nearly terete, segments strongly arched above and slightly flattened below. Notocirrus a small globoid or siibcylindrical papilla situated on the side of the body well above the parapodium.
Simultaneously with the development of the dorsal gill, a ventral gill develops from the modification of the neurocirrus.
GONIADID^
No, the specimen had more than a small portion of the proboscis protruding and the jaws were seen by dissection. Parapodia are located anteriorly near the ventral level and extend for the entire depth over most of the posterior region, all long and slender, while those at the anterior end of the anterior region and throughout the entire posterior region are similar to the width of the segments or, near the caudal end, exceed them. In somite XXX, a small notopodium appears abruptly anterior to the base of the notocirrus and immediately consists of a small setigerous tubercle, a short preset allip, and a longer postsetal lip.
Through the remainder of the anterior region the biramous parapodia undergo no apparent change, but with the onset of the posterior sexual region (about somite LXX to LXXVI) they become markedly larger and the rami better differentiated. The notopodium consists of a deep postetallip broadly attached to the thenotocirrus above, with a slight deflection at the tip of the aciciculum, and a small subovate parasetal lip or process just ventrally to the end of the aciciculum. They are shortest at the dorsal and ventral borders of the fascicles and gradually increase in length to the acicular borders.
These bands extend almost the entire length of the reversible proboscis, from the jaws almost to the base. The ventral bands are borne by a pair of rather sharp ridges and each consist of two series of horny papillae, those of the more medial series (PI.. XXI, fig. 167) being larger with broad crescent-shaped, flat bases and slightly curved , sharp, conical tips. The papillae of the dorsal bands are larger and thicker, especially those of the inner or more medial series, which are claw-like, directed towards the midline, with a broad base and a subapical pore (Fig. 169).
All these papillae are very hard and horny and continue towards the jaws without decreasing in size, but gradually become smaller in the opposite direction, towards the base of the proboscis. The general color of the type is bright amber brown, with the furrows and middorsal field being blue-gray and the prostomium light gray. At XVI, coinciding with the shift of the parapodia dorsad, the segments become much shorter and deeper.
Parapodia beginning I and arebiramous throughout, the first fifteen differing from the others in the lateral position and large size of the neuropodium and the fimbriated or pectinated postsetal membrane. Apart from gradually shifting dorsadward and becoming larger, with a conspicuous asymmetric wing on the ventral side of the base, the notopodial postsetal lobe undergoes no change in the anterior region.
313 remain much as described, the presetal short and truncate, the post-
On the posterior region, the more slender and elongated setse have the structure of the lake. In the neuropodium, after a few somites it is clear that the shorter etae of the first tendril two have become darkly stained and have lost both the external serration and the internal cavity. The setae of the posterior rows are of the same type as the non-opodial setae, but the basal canalization and cameration are more pronounced and the slender, fixed points are no longer elongated.
In the posterior region, the neuropodial processes have the exact structure of the tenotopodium, but are fewer. The branches in all specimens begin at some point and rise from the dorsal region as a pair of leafy, rather broadly lanceolate processes, scarcely reaching the notopodium, and separated from each other by a distance greater than their length. XXI, fig. 172) to somite XL, their length is about three-fifths of the body width, their shape is lanceolate and they are held upright. In the posterior part, they become fully one and a half times larger than the width of the body and taper into threadlike tips.
Anteriorly the gills are quite free from each other and from the notopodia, but as the parapodia assume the dorsal position they are united by a transmembranous fold crossing the entire width of the back. The proboscis is very imperfectly known, only the ends of a few of the lacinate divisions being exposed on any of the specimens. Another conspicuous series of median dorsal brown spots begins on VII and continues to the caudal end.
The only other color is a slight anterior cuticular iridescence, the indistinct eye spot (?) on each side of the prostomium, and a darkening of some of the palisades of the setae.
