140 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



ABC D 



Fig. 33. — Stenoscisma sp., Hess Formation, Glass Mountains, Tex., transverse 

 sections X4. 



A. Spondylium nearly sessile, septum thick, with wedged insertion into floor ; 

 hinge plate and cardinal process thick, form indistinct. B. Cardinal process 

 high, edges of spondylium broken. C. Duplex intercamarophorial plate attached 

 to hinge plate and crural bases. D. Crura extend anterior to hinge plate. 



shorter, occupying remainder of camarophorium. Pallial trunks orig- 

 inating in posterior of valve, diverging anteriorly, each bifurcating 

 several times toward margins, there each branch splitting into several 

 and radiating across stolidium. 



Type species. — Terebratula schlotheimi von Buch, L., 1835, Akad. 

 der Wissenschaften, Berlin, Abhand., Jahrgang 1833, p. 59-60, pi. 2, 

 figs. 32a-c ; by monotypy in Conrad, T. A., 1839, Geol. Survey New 

 York, 2d Ann. Rept., Assembly Document 275, p. 59. 



Discussion. — Stenoscisma is the most important and most abun- 

 dantly represented genus in the Stenoscismatacea. Its greatest devel- 

 opment occurred in the Permian; more than 60 Permian species had 

 been described by 1948 (Branson, C. C, 1948), and fully 20 more 

 have been discovered since then, both published and unpublished. The 

 genus was worldwide, an important constituent of nearly all Permian 

 brachiopod faunas. 



Only a few species are described here as examples of the genus. It 

 would be futile to try to comment meaningfully upon every species; 

 such full treatment would add little to the understanding of this well 

 known genus whose descriptions in the literature are numerous. Ex- 

 amples chosen are the type species, S. schlotheimi (von Buch) abun- 

 dantly represented in the collections of the U.S. National Museum and 

 Yale Peabody Museum, a few species from the Permian of West 

 Texas, known from the work of R. E. King (1931), Girty (1909, 

 1929) and Stehli (1954) and represented by abundant and/or well 



