NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT 67 



Fig. 11. — Camerisma prava n. sp., Mississippian, Ladrones Islands, Alaska; 

 transverse sections X4, USNM 142072, original length 15.0 mm., measurements 

 from pedicle valve beak. 



A. 2.0 mm. : cardinal process low. B. 2.6 mm. C. 2.7 mm. : camarophorium, 

 intercamarophorial plate, and septum of spondylium all duplex, with wedged in- 

 sertion of septa into shell. D. 3.0 mm. : hinge plate thin, crura visible, camaro- 

 phorium slightly thickened at base of septum. 



complete lack of costae, sharp fold and sulcus, and asymmetry. It is 

 smaller than the other Mississippian species from Alaska, C. girtyi n. 

 sp., and is wider, has a higher, narrower, sharper fold, and is strongly 

 asymmetrical. It differs from the species C. sagmaria n. sp. from 

 the Permian of Yugoslavia, in its much larger size, wider and asym- 

 metrical outline, sharper fold, and lack of any trace of costae. 



C. prava resembles C. ? sella (Kutorga) in its broad outline, sharp- 

 crested fold, and similar size. It differs from Permian species in its 

 longer, thick pedicle beak, somewhat lower fold and in its pronounced 

 asymmetry. Similarity of the two species, despite their age difference, 

 argues for inclusion of C. f sella in the genus Camerisma. 



Occurrence and abundance. — Unnamed Upper Mississippian lime- 

 stone of Condon (1961), Craig Quadrangle, Southeastern Alaska, all 

 specimens collected by G. H. Girty in 1918: U.S.G.S. loc 3779, white 

 massive limestone at south end of island No. 205 in Ladrones Islands, 

 three specimens (USNM 142072-74). 



CAMERISMA GIRTYI Grant n. sp. 



Plate 8, figs. 3-3a ; figure 12 



Shell somewhat large for genus, adults strongly biconvex ; outline 

 subtrigonal to subelliptical, transverse in young specimens, elongate in 

 adults, juveniles widest near midlength, adults widest farther anterior ; 

 commissure uniplicate ; fold moderately high, becoming very high in 

 largest specimens, with bluntly pointed crest, in shape of Gothic arch, 

 standing only slightly above flanks ; sulcus rather shallow, with sharp 

 median trough ; costae absent from flanks, one weak costa on each side 

 of fold, with corresponding shallow troughs on each side of sulcus, 



