120 



MOLLUSCA. 



No. 320. Corralliochama Orcutti, White. 



This new genus of the family Chamidse has been 

 lately described by Dr. C. A. White, from Middle 

 Cretaceous fossils of California. 



It agrees with Caprina, and other genera, in the 

 general character of the hinge and of the ligamental 

 grooves, and the presence of an outer prismatic shell- 

 layer. The test is thick, of three layers, the outer 

 prismatic, the middle cellular, and the inner porcel- 

 lanous. The middle layer constitutes the bulk of 

 both valves, and has a tubular structure which causes 

 the fossil to somewhat resemble the coral Favozites. 

 The shells grow separately or in clusters, fixed by 

 the apex of the lower or right valve. From the 

 shore of Todos Santos Bay, Lower California. 



No. 321. [055, Cast]. Hippurites radiosa, Desmoulins. 



The Hippuritidffi, to which family this form belongs, are 

 entirely extinct and confined to the Cretaceous strata. They 

 have an unequivalved, unsyrametrical shell, with two mus- 

 cular impressions, and are the most remarkable and problem- 

 atic of fossil Lamellibranchs. 30 species of the genus are 

 known. This specimen, showing both valves, is from the 

 Lower Chalk, Dordogne, France, and is now in the Ward 

 Collection, University of Rochester. Size, 6x4. 



No. 322. [659, Cast]. Radiolites (SphcErulites) crateriformis, d'Orb. 



Lower Valve. This genus belongs to the 

 strange family Hippuritidai; 43 species are 

 known. This specimen shows the peculiar 

 form of growth which this shell undergoes, 

 the whole organism being much modified — 

 from the normal bivalve construction — by its 

 sessile character and its permanent attachment 

 to the rock on which its station was chosen in 

 an earlj^ period of its development. This 

 lower valve shows the several lines of its 

 foliaceous growth, as also the "birostre," or 

 the central cavity. From the same locality and 



Size, 6x6. 



internal mould, still fillint 

 Museum as the preceding. 



