PELECYPODA—TELEODESMACEA. 



551 



CXLIX. Ichthyosarcolites Desm. 

 Fixed by right valve or free. Composed of a thick layer of 

 open tubes with a thin superficial lamina. Cartilage internal, con- 

 tained in several deep pits. Umbos more or less chambered. 

 Right valve conical or elongated, with ligament furrow on the 

 convex side. Hinge with one oblique plate. Left valve oblique 

 or spiral ; hinge with two teeth, the anterior supported by a plate 

 which divides the umbonal cavity lengthwise. Comanchic. 



522. I. anguis Roemer. (Fig. 754.) Comanchic. 

 Lower valve elongate, snake- like, at times a foot long and over 



one inch thick. Ligament 



furrow runs entire length 



of shell. Transverse sec- , , ,.iw « , 



tion of valve oval or subtri- £ jflK^ jS W& J 



gonal. Upper or free valve 



spirally once enrolled. 



Upper Fredericksburg : 

 Texas. 



CL. CORALLIOCHAMA 



White. 

 Shell a large cone fixed 

 by apex of lower (right) 

 valve growing separate or 

 in clusters, thick, of three 

 layers, the outer prismatic, 

 the middle cellular, the in- 

 ner porcelainous ; lower 

 valve irregularly conical, 

 somewhat distorted, upper 

 valve convex with broad 

 incurved beak. Hinge sim- 

 ilar to preceding. Cretatic. 



523. C. orcutti White. 



(Fig. 755.) Cretacic. 



Type of genus. The cel- 

 lular portion of the shell 

 resembles Favosites. (See 

 Bull. U. S. G. S. No. 22.) 



Fig. 755. Coralliochama orcutti ; a, complete 

 adult shell ; b, diagram of transverse section of 

 lower valve, showing outer prismatic, inner por- 

 celainous and middle cellular layers; c, section of 

 part of upper valve ; d, fragment of lower valve 



showing cellular structure. 

 White.) 



All, XH- ( Aft er 



