330 Annals of the Carnegie Museum. 



typical specimens of that species were from the Black River (Lowville 

 division) at Pointe Claire and Osnabruck. 



The Ctenodonta nasuta of Billings was probably a different species 

 from that described by Hall, and may be the Ctenodonta parvidens 

 or C. peracuta of the present paper. 



In Professor Hudson's paper/^ two more lamellibranchs are de- 

 scribed. These are Modiolopsis suhquadrilateralis and Cyrtodonta ? 

 lamellosa, both small and rare species, so far found only at the type- 

 locality. 



In 1905 the writer^^ described, without figures, thirteen species of 

 pelecypods, which he supposed were from the Chazy, but further study 

 has shown that two of them were from the overlying formation. In 

 1906^' he added four more species, also without illustrations. 



In 1908, Dr. J. F. Whiteaves^" described several pelecypods sup- 

 posed to have come from the Chazy, but recent field-work has shown 

 that most of these, including all his new species, were derived from 

 the Pamelia. In this paper, Modiolopsis parviuscida and Cyrtodonta 

 brevinscuJa were figured for the first time. 



Sub-Kingdom MOLLUSCA Linnajus. 



C\^ss PELECYPODA Goldfuss. 



Order PRIONODESMACEA Dall. 



Family Ctenodontid^ Dall. 



Genus Ctenodonta Salter. 



I. Ctenodonta peracuta Raymond. (Plate XXIX, figures 1-3.) 



Cf. Nucula levala Hall, Paleontology New York, Vol. i, 1847, p. 150, figs. if-i. 

 Ctenodonta levala Raymond, Bulletin of American Paleontology, Vol. Ill, 1902, 



No. 14, pp. 14, 15, 19. (In lists.) 

 Ctenodonta peracuta Raymond, American Journal of Science (Ser. 4), Vol. XX, 



1905. P- 371- 

 Since this species was originally described, a fragment of a free 

 shell has turned up in the loose material in the fault on Valcour 



1' Report of the N. Y. State Paleontologist for 1903 (1904), p. 286. 

 ^^ American Journal of Science, Vol. XX, (Ser. 4), 1905, pp. 371-374. 

 1' Annals Carnegie Museum, Vol. Ill, 1906, pp. 577, 578. 

 20 Ottawa Naturalist, Vol. XXII, 1908, p. 105. 



