274 PROCEEDINGS OF THE ACADEMY OF 



Actseon, while the lower is more oblique and winds around the 

 columella more like that of Cylichna. 



C. bidentata. d'Orb. 



Bulla bidentata, d'Orb. La Sagra's Cuba, pi. fig. 13, 16. 



Utriculus bidentatus, Cheinn. Mar. Conch., vol. 1, p. 388. 



ACEPHALA. 



CORBULID.E. 



BoTnROCORBPLA, Gabb, pi. 10, fig. 3, 3 a. 



Shell like Corbula in every respect, except that it has a deep 

 lunular pit under the beaks penetrating and almost passing through 

 the hinge plate. 



I have carefully examined almost all of the living and many 

 fossil species of Corbula, and can find in none the slightest trace 

 or rudiment of a lnnuli ; while this shell has it deeper than I have 

 even seen in any other form, except in Here of the Lucinus. 



B. viminca, Guppy, sp. 



Corbula viminca, Guppy, Quart. Journ. Geol. Soc. Lond., v. 22, p. 293, 

 pi. 18, fig. 11. 



ANATINID.E. 



Ne.eromya, Gabb, pi. 10, fig. 4, 4 a, 4 b. 



Shell thin, translucent, in shape approaching Pholadomya, ends 

 closed ; hinge with a prominent tooth in the right valve, articu- 

 lating behind a smaller similar one in the left valve; an anterior 

 and posterior lateral tooth in each valve. Mantle margin without 

 sinus. 



This genus, in its thin character and minute hinges, is elosety 

 allied to Pholadomya, Thetis, and Nesera, but differs from all in 

 details of the hinge. Neeera has no cardinal tooth, but, in its place, 

 a cartilage pit in each valve. It has a single posterior tooth, 

 while this genus has the anterior equally well developed. In 

 having corresponding teeth in both valves, it differs from Thetis, 

 while its well specialized hinge and its closed ends distinguish it 

 from Pholadomya. 



JV. quadrata, Gabb. 



