MUSEUM OF COMPARATIVE ZOOLOGY. 227 



variety is evidently a more southern form and looks specifically distinct, but 

 having only a few separate valves it seems better to wait for more material, 

 which may prove more nearly intermediate. If distinct, it may be called 

 L. lata. 



Family SPONDYLID^E. 



Genus SPONDYLUS Linn^. 



Spondylus Gussoni Cqsta. 



Spondylus Gussoni Costa, Cat. Sist., p. xlii, 1829 ; Phil., Moll. Sicil., I. p. 87, pL v. 



f. 16, 1836. 



Found at Station 150, near Xevis, in 375 fms. ; at Station 193, in 169 fms. ; 

 at Station 278, Barbados, in 69 fms.; at Station 262, Grenada, in 92 fms. ; and 

 in 640 fms., Yucatan Strait. 



The specimens have been compared with authentic European examples, and 

 agree precisely. 



Genus PLICATULA Lamarck. 

 Plicatiila spondyloidea Meuschen. 



Ostrea spondyloidea Meuschen, Mus. Gronovianum, 1778. 



Plicalula ramosa Lamarck, An. s. Vert., ed. i., VI. p. 184, 1819. 



P. marginata Say, Journ. Acad. Nat. Sci. Phil., IV. p. 136, pi. ix. f. 4. 



Found in 36 fms. at Station 12 ; in 54 fms. off Sombrero Island; and in 

 640 fms. in Yucatan Strait; in the last case probably ejected by a fish. 



This extremely variable shell has been erected into a number of species. It 

 varies from nearly smooth to strongly plicate; from greenish white to closely 

 streaked with brown. The young are rather pretty, the old ones coarse and 

 rude. The number of ribs is most numerous when the shell is attached to a 

 flattish surface ; the ribs are fewest and most coarse when the shells grow on 

 one another like reef oysters. 



Family DIMYID.^. 



Genus DIMYA Rouault. 



Dimya Rouault, Mem. See. Geologique de France, 2me ser., III. p. 471, 1848. 



Stoliczka, Cret. Pelec. of S. India, Pal. Indica, III., ser. vi., pp. xxii, 397, 1871 ; 

 {Aviculidce, subfamily Vulsellina). Dall, Science, Feb. 16, 1883, p. 51. 



Woodward, Man. Moll., 2d ed. by Tate, p. 408 {Oslreida), 1871. 

 Margariona (Dall, Ms. 1882), Kobelt, Naclir. Mai. Ges., p. 186, 1882. 

 Type Dimya Deshayesiana Rouault. 



