The main features of the genus are the peculiar granulose wall structure and the presence of cystiphragms in both axial and peripheral regions. In tangential sections, the zocecial walls exhibit the usual granulose structure characteristic of the genus. Figures of the external characters of these species are given in the Columbia Tennessee folio, recently published by.
This species differs from all others of the genus in its small zooecia, very numerous acanthopores and closely spaced mon-. Occurrence.— Nothing unusual in the shaly lower half of the Lexington Limestone at Trenton near Frankfort.
Cyphotrypa new genus : — Zoarium massive or laminar, never
Hctcrotrypa Nicholson: — Zoarium erect, frondescent; acanthopores of one species; little; mesopores varying in number, generally abundant, sometimes almost entirely lacking.
Diaphragms few or wanting
Dckayia Edwards and Haime :— Zoarium erect, irregularly ra-
It is an interesting fact that in all essential respects the structure of the walls of Hcterotrypidtc, when compared in tangential sections, is practically the same as that of the cryptostomatous genus Escharopora. According to his conception, Monticulipora frondosa is based on the species Homotrypa, which occurs as a relatively rare fossil in the upper layers of the Lorraine Formation. The boules from the D'Orbigny type lot are also of the same type as those represented by the Edwards and Jaime figural specimens.
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Cyphotrypa new genus: — Zoarium massive or laminar, never
Dckayia Edwards and Haime : — Zoarium erect, irregularly ra-
Cuming, in a recent revision of the genera Dekayia, Dekayella and Heterotrypa, concluded that they represent one and the same generic type, and also believes that Ulrich's identification of Monticidipora frondosa, the genotype of Heterotrypa, is incorrect. Boule of D'Orbigny's lot type is also of the same species as that represented by the depicted specimen of Edwards and Haime. It is true that Ulrich put forward the idea of combining the three genera several years ago, but this was at a time when Dekayella was the only genus of the three species known in the Mohawkian.
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Moreover, we have started to pay more attention to the tabulation of the tubes and with satisfactory results in the way of natural classification. From the Stones River group onwards the genus is represented in almost all divisions of the Ordovician. Prevent. - Common in the shaly limestone at the top of the Trenton on Reservoir Hill, Frankfort, Kentucky.
The periodic development of the acanthopores and thickening of the walls separates the new genus from Dekayia with which it corresponds in the sparse development of diaphragms. Occurrence.— Very abundant in the lower part of the Richmond Formation of Hanover, Butler County, Ohio. It is one of the non-mesopored species of the genus and forms smooth, branching zoaria much like .V.
From the first, it can be distinguished that there are fewer acanthopores, no mesopores and in the absence of crimulation of the walls in the immature region. The surface is often sharp due to the acanthopores which, although quite numerous, are small. This new species is easily distinguished from all described forms of the genus by its uniform method of growth.
Occurrence.— The types are from arrowheads at the top of the P.ighy limestone of Trenton in Columbia, Tennessee, where the species. Occurrence.— The species is from the Constellaria Bed at the top of the Bigby Limestone at Columbia, Tennessee, where specimens can be found literally by the million. Lioclema punctatum is a very abundant fossil in the Keokuk formation of the Mississippi valley, and strictly stunted in growth habit.
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Leptotrypa discoidea (Nicholson) is not so easy to care for, we are still undecided as to whether it belongs to Integrata or Amalgamata. If it is of the first-mentioned type, then it is still a question whether it will not be advisable to recognize another genus for it. The correctness of referring massive as well as ramose species to this genus is also confirmed by the close relationships between two of the following.
As to the geological range of the genus, it now appears that it extends no further than the top of the Ordovician. We hope to discuss these at a later date in connection with the rest of the Devonian Trepostomata. Zoarium enormous, usually subglobose, a diameter of an inch or more; rarely is the growth irregular, resulting in shapeless ma^e-.
Surface without monticulae, but showing macules composed of zocecia reaching nearly twice the diameter of the median cell. Zooecial apertures polygonal, 6 to 7 of which occupy intermacular spaces to 2 mm; thin-walled, not unfrequently showing acanthopores, which, in the fully mature state, recurring at intervals during the growth of a colony, are quite large, well defined, and about half as large as the angles of intersection with which they are almost complete. limited.
42 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 In tangential sections the walls present the sharply-defined median
After numerous failures to identify another specimen of this species, we were led to believe that the original type was unique. Because of the extreme rarity of the genotype, Monotrypella was known to collectors only by M. A true mesopore is absent, but interzoecial spaces without walls occur in several species.
The most important characteristic of the genus is the rhombic shape of the axial tubes in cross section. The smooth spaces represent the fiat side of a series of tubes coincident with the plane of the fracture. In the uneven spaces, the angles and the two sides of each of the pipes are exposed.
In the latter case, the plane of the sides of the pipes and consequently the rows form an angle of approx. 45 degrees with the plane of the fracture. The interpolated new tnhes maintain the triangular shape necessitated by the shape of the spaces at their disposal until the next period of gemination causes another turning and interpolation of another set of young tubes. The development of new tubes ceases completely with the entrance of the older tubes in the peripheral zone.
This is also true of practically all other ramose trepostomata, and, as a rule, only after the cessation of generation does the growing space available to the zocecia, which naturally results from peripheral growth in this area, admit the development of mesopores and acanthopores.
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Generic diagnosis. Zoarium ramose or subramose; zocetia polygonal to rounded with walls thin, iridescent and ring-shaped in the axial region, slightly thickened and flat in the peripheral region. Another characteristic that applies to all species observed so far is the pronounced crenulation of the zocecial walls in the immature area. When such fractures are examined under a hand lens in good light, a beautiful overflow of the zocecial tubes can be seen.
How important this may be in a generic sense cannot be said, but since all species exhibit this characteristic we see no reason why it should not be included among the generic characteristics. Vertical fractures show the crenellated walls and iridescence discussed in the discussion of the genus. There are differences, compared to Calloporidce – in the development of the zocecia, in the mesopores and in the acanthopores – that require some recognition, and as now.
The next new genus requires a modification of our previous conception of the family, in that non-tabulated zooecia are admitted. Internal characters. In vertical sections, the striking feature is the absence of apertures in both the zocecia and the mesopores. In the axial region the walls are thin and wavy, while the tilt is long and not as frequent as in the species of Calloporina.
With the onset of the mature region, the walls become greatly thickened and considerable laminated tissue develops on the inner sides.
EXPLANATION OF PLATES
47notable feature; they differ only in the size of their zoecia, a noticeable feature; differ only in the size of their zocetia,. Acanthopores appear to be small, few in number, and located at the junctional angles. The rather large angular zocetia, thick walls and few mesopores, and, more satisfactorily, the absence of diaphragms, distinguish this species from otherwise similar related forms.
Tangential section, X20, showing the angular shape and thin walls of the zooecia and the relatively few mesopores. Vertical section, X20, showing the superficial limbs of two zooecial tubes and a case where the mesopore lyre occurs further down the section, appearing to be expressed. 6 Vertical section, X 20, passing through two mature regions with an immature zone between and showing the congested diaphragms characteristic of this species.
The figure shows an average of the development of acanthopores, mesopores and the thickness of zooecial walls. X 20, showing the aged state in which the prisons are thickened, the mesopores reduced to a minimum, and.
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The lower curved line represents the outer surface of the crinoid stem over which the colony grew, while the shaded portion above it represents a clay-filled intei space. Vertical section, X 20, illustrating the periodic development of the acanthopores and the extreme infrequency of the diaphragms. Small part of a tangential section, X 40, where it passes through one of the zones of acanthopores.
Tangential sections, X35 and X20, illustrate the wall structure and the distribution and character of the acanthopores and mesopores. 47Catheys Limestone of the Trenton, Love Branch, Maury Catheys Limestone of the Trenton, Love Branch, Maury County, Tennessee. Tangential section, X 20, showing the angular zocecia, relatively few and small acanthopores, and almost total absence of mesopores.
Part of the mature region of a vertical section, X 20, showing the usual position of the membranes. Tangential section of twozocecia, X35, showing the full development of acanthopores and the characteristic dark median line.
