148 



GENERA OF THE SUBORDERS ORTHOIDEA AND PENTAMEROIDEA 



a small sinus in the dorsal fold and a plication in the 

 sulcus, by enlargement of said plication. While this 

 is possible, the fact remains that Parenteletes was devel- 

 oped earliest. Furthermore, there is much more simi- 

 larity between Orthotichia and Parenteletes in the 

 divergence of the dental plates. Therefore the evi- 

 dence points to an independent development of the two 

 genera out of Orthotichia. 



E. suessi, figured by Schellwien,^^^ we place in asso- 

 ciation with American species of Parenteletes, as it 

 shows, according to his figure, the same internal char- 

 acteristics as the American forms. ScheUwien re- 

 marked on the external similarity between E. suessi 

 and the Indian E. latesinuatus Waagen, but pointed 

 out the internal differences and on this basis separated 

 the two species; his figure shows the walls of the 

 camera uniting with the dental plates, but in American 

 forms these are discrete. There is a possibility that 

 the figure has not been drawn accurately. 



The camera of Parenteletes is a remarkable con- 

 vergence toward the type of muscle platform in 

 Merista, Dayia, and Cyclosfira, although the one in 

 Parenteletes differs in bearing a median septum on its 

 crest. 



Genus ENTELETINA Schuchert and Cooper 

 1931 



PI. 24, figs. 17, 19, 20 



Schuchert and Cooper, Amer. Jour. Sci. (5), vol. 22, 1931, 

 p. 247. 



Genoholotype. — Enteletes latesinuatus Waagen 

 1884, Mem. Geol. Surv. India, Pal. Indica, ser. XIII, 

 vol. 1, pt. IV, fasc. 3, pp. 559-560, pi. 57, figs. 4-6. 



Description. Exterior. — Externally Enteletina is 

 identical with Parenteletes but internally it has all of 

 the features of Enteletes. It therefore is essentially an 

 Enteletes with the fold on the ventral valve and com- 

 prises Waagen's division of "dorsosinuates." The 

 dental plates are not strongly divergent and there is a 

 crested median septum which does not have the peculiar 

 V-shaped camera so characteristic of Parenteletes. 

 The presence of this chamber, the function of which is 

 not understood unless it be for muscle attachment, is 

 therefore not a distinction between the Asiatic and 

 American and European "dorsosinuate" Enteletes. 



The writers have selected Waagen's species E. late- 

 sinuatus to serve as the genotype, as both internal and 

 external characters of it have been admirably figured. 

 The Indian forms are all Upper Permian in age and 

 may represent a development from Enteletes by the 

 enlargement of plica5 in the ventral sulcus, such as sug- 

 gested by Waagen and Girty. (See under discussion 

 of Parenteletes.) We have placed in this genus only 



"'Abh. k. k. geol. Reichsanst., Bd. 16, Heft 1, 1900, 

 p. 12, pi. l,fig. 18. 



the Late Permian species of India, and do not include 

 here such Pennsylvanian and Lower Permian forms as 

 E. suessi and variety acuticosta and E. dieneri, since 

 their internal structure is clearly that of Parenteletes. 



Enteletes globosus Girty, probably from the Word 

 of late Middle Permian age, is placed here provisionally 

 since its internal structure is not known. 



Geologic range. — Permian of India and Texas. 



Indian Species 



Enteletes acutiflicatus Waagen 1884 

 E. jerrugineaWiigtn 1884 

 E. latesinuatus Wiigen 1884 

 E. fentameroiJes Waagen 1 884 

 E. suMirvis WiAgen 1884 



American Species 

 ? Enteletes globosus Girty 1908 



Genus ENTELETELLA Likharev 1924 



PI. 24, fig. 4 



Likharev, Bull. Com. Geol., Leningrad, vol. 43, no. 6, 

 1924, pp. 719, 721, pi. 5, figs. 1-3. 



Genoholotype. — E. nikschitschi Likharev 1924. 



Description. — Enteletella has the external form 

 and ornamentation of a ventrisinuate or true Enteletes, 

 closely resembling E. microflocus Gemmellaro. It 

 differs internally from Enteletes, however, in the 

 possession of a spondylium. The dental plates unite 

 with the median septum in such a way as to enclose a 

 portion of it, which projects as a ridge for the attach- 

 ment of the adductors inside the spondylium. The 

 dorsal edge of this ridge is somewhat club-shaped, and 

 the lower part of the median septum remains free. The 

 dorsal valve is, in all respects, the same as that of 

 Enteletes. The genotype is the only species known. 



Geologic range. — Lower Permian of northern 

 Caucasia. 



Genus ENTELETOIDES Stuckenberg 1905 



Stuckenberg, Mem. Com. Geol., n. sen, livr. 23, 1905, 

 pp. 59, 129, pi. 6, fig. 8, pi. 9, fig. 8. 



Gorsky, Bull. Com. Geol., vol. +3, no. 9, 1927, pp. 1184- 

 1186, pi. 18, fig. 7 (subrossicus) . 



Genoholotype. — E. rossicus Stuckenberg 1905. 



Distinguishing characters. — Stuckenberg pro- 

 posed this name for shells having a convexo-concave 

 profile and multicostellate external ornamentation, 

 recalling Orthotichia in both of these characteristics. 

 According to that author the shell completely lacks 

 interareas. Internally the arrangement of the dental 

 plates and median septum is identical with that of 



