146 



GENERA OF THE SUBORDERS ORTHOIDEA AND PENTAMEROIDEA 



stocks and therefore of use in the definition of two 

 genera along with other features. 



The evolution of the Enteletinae is somewhat analo- 

 gous to that of the Derbyias and Meekellas which 

 lived at about the same time. In the last named 

 genus the shell also develops broad undulations at the 

 front as in Enteletes. It would be interesting to know 

 what conditions of ecology in the Pennsylvanian and 

 Permian seas could have produced such parallel devel- 

 opments in these two different stocks. Or is it an 

 expression of old age in these terminal stocks that 

 arose so far back in the Ordovician? 



Table 15 

 Ente etina 



Enteletes 



Parenteletes 



* Enteletella 



Enteletoides 



Schizophoria 



Genus ENTELETES Fischer de Waldheim 

 1825 



PI. 24, figs. 1-3, 5-10, 25 



Fischer de Waldheim, Notice sur la Choristite, 1825, p. 6; 

 Oryct. Gouv. Moscou, 1830-1837, p. 144, pi. 24, 

 figs. 10-11 {choristites ^^ lamarcki) , pi. 26, figs. 6-7 

 {glaber). 



Genoholotype. — E. chorhtltes Fischer de Wald- 

 heim 1825 =^Sfirifer lamarcki. 



Description. Exterior. — More or less globular, 

 margins convex; hinge-line narrower than the great- 

 est width of the shell; cardinal extremities rounded; 

 lateral profile unequally biconvex, the dorsal valve 

 being the more convex; lateral commissure dorsally 

 deflected near the hinge; anterior commissure unipli- 

 cate; ventral interarea the longer, curved, apsacline, 

 beak strongly incurved, umbo swollen; dorsal inter- 

 area short, curved, orthocline to apsacline, beak 

 strongly incurved, umbo tumid; delthyrium open. 



notothyrium partially closed by the cardinal process. 

 Surface finely costellate, and plicate anteriorly. Shell 

 fibrous, punctate. 



Ventral interior. — Umbonal cavity deep ; teeth 

 strong ; crural fossettes oblique ; dental plates strongly 

 developed, advancing, slightly convergent or subpar- 

 allel; the space between these plates divided medianly 

 by a thin bladelike septum rising to an apex at its 

 anterior extremity, truncated sharply in front so that 

 it terminates in a line with the anterior termination of 

 the dental plates; muscle area compressed laterally; 

 diductors and adjustors confined to the narrow areas 

 between the dental plates and the septum, while the 

 adductors were probably attached to the latter. 



Dorsal interior. — Cardinalia strong; brachiophores 

 strong, curved, supported by thin plates that are ex- 

 tended forward and around the lateral margins of the 

 muscle area as far as the anterior margin. Sockets 

 strong, defined by a socket-plate on the outside margin 

 of the socket; along the hinge-line a strong denticle; 

 cardinal process small ; muscle area like that of Ortho- 

 tichia, the anterior adductor scars large, subcircular; 

 the posterior adductors forming two small scars on the 

 outside of and slightly posterior to the anterior adduc- 

 tors and next the ridges from the brachiophore 

 supports. 



Geologic range. — Middle Pennsylvanian to Per- 

 mian in many parts of the world. 



American Species 



Enteletes andii {T>'Oih\gnY) 1842 

 E.dumbleiGnxy 1908 

 E . hemiflicata ( H all ) 1852 

 E.leonardensis King 1930 (= 1931) 

 E.Uumbonus King 1930 (= 1931) 

 E.flummeri King 1930 (= 1931) 

 E. u'oljcamfensis King 1930 (= 1931) 

 E.wordensis King 1930 (= 1931) 



Foreign Species 



Enteletes contractus Gemmellaro 1 898 



E. elegans G&cameAixo 1898 



E. haugi Gemmellaro 1 898 



E. hemiflicatus naia Fredericks 1923 



E. kayseri Waagen 1 884 



E . Itevissimus Waagen 1884 



E. lamarcki Fischer de Waldheim 182 5 



E. meridionalis Gemmellaro 1 898 



E. microflocus Gemmellaro 1 898 



E . oehlerti GemmcWiTO 1898 



E . subiiquivalvis Gemmellaro 1898 



E. tschernyscheffi Diener 



E. waageni Gemmellaro 1898 



? E. fentamera Eichwald 



Distinguishing characters. — Enteletes is dis- 

 tinguished externally by its elliptical outline, globular 

 profile, and plicate anterior. Internally the subpar- 

 allel dental plates and sharp, crested median septum 



