WHITE.] 



CRETACEOUS. 297 



Ostrea lateralis Nilsson. 



Certain autliors have regarded the Ostrea vomer of IMortou as identical 

 with the European one described under the name 0. lateralis by Nilsson. 

 I regard them as distinct. (See remarks under the head of Ostrea vomer 

 on a following page.) 



Ostrea littlei Gabb. 



Under this name Mr. Gabb described a form without illustration, in 

 the Proceedings of the Academy of Natural Sciences of Philadelphia 

 for 1876, page 321. It is reported from the Cretaceous of Georgia. 



Ostrea lugubris Conrad. 



(Plate LI, Fig. 3.) 



All the known examples of this species are so small as to suggest that 

 they may be the young of a larger species ; but it seems to be very con- 

 stant in size and in other general characteristics. It is common in cer- 

 tain of the Cretaceous rocks of Colorado and NewMexico. It was orig- 

 inally published in the report of the United States and New Mexican 

 Boundary Survey, Vol. I, page 156, Plate X, Figs. 5 «, h. 



Ostrea lyoni Shumard. 



Dr. Shumard published this form from the Cretaceous strata of Texas, 

 without illustration, in the Proceedings of the Boston Society of Nat- 

 ural History, Vol. VIII, page 200. Similar mention has been made of 

 other species which have been published without illustration. It is diffi- 

 cult at best to correctly illustrate a species of the Ostreidse even by the 

 use of numerous and well preserved examples; and in the present state 

 of publication of the fossil forms it is almost impossible to identify any 

 species, even a well-marked one, by a written description only. 



Ostrea malleiformis Gabb. 



(Plate L, Fig. 8.) 



Mr. Gabb obtained this species from the Cretaceous rocks of Cali- 

 fornia, and published it with one figure in Vol. II of the Paleontology 

 of that State, page 201, Plate 31, Fig. 272. 



It is characterized by wing-like expansions of the cardinal portion, 

 and seems to be a well-marked species. 



Ostrea mesenterica Morton. 

 (See remarks under the head of Ostrea larva on. a preceding page.) 



Ostrea mortoni Gabb. 



Mr. Gabb described this form as coming from Cretaceous strata, but 

 Professor Heilprin regards it as a Tertiary species. (See his remarks 

 under the same head on a following page.) 



