300 Proceedings of the Boyal Physical Society. 



ventral margins. Professor Dana's specimen measured three 

 and a half inches in length, but the shell I refer to N. recta 

 measures seven and a quarter inches in the same direction. 

 Like all the bivalves in Mr Jack's collection the state of 

 preservation is very bad, but there appears to be the remains 

 of an obscure posterior slope, a character which I do not find 

 mentioned in Dana's description. 



Loc. and Horizon. — Coral Creek, below Sonoma road- 

 crossing, in a yellow, micaceous, decomposed ironstone (No. 

 116). 



Collector.— V^.. L. Jack, Esq., F.G.S. 



Genus Pachydomus — Morris, 1845. 



(Strzelecki's "Physical Descrip. N. S, Wales," etc., p. 271.) 

 Pachydomus (?) carinatus — Morris. — PI. XVI., fig. 53. 



P. carinatus, Morris, Strzelecki's " Phys. Descrip. N. S. Wales," 1845, p. 273, 



t. 11, f. 3 and 4. 

 Cypricardia rugulosa, Dana, American Jour. Sc, 1847, iv., p. 157. 

 P. carinatus, M'Coy, Annals Nat. Hist., 1847, xx., p. 301. 

 McBonia (?) carinata, Dana, Geology U.S. Expl. Exped., p. 696, Atlas, t. 6, 



f . 1 a and h. 

 PUuropliorus (?) carinatus, De Koninck, Foss. Pal. Nouv-Galles du Sud., 



1877, pt. 3, p. 283, t. 19, f. 8. 

 Pachydomus carinatus, Etheridge, jun,, Cat. Australian Foss., 1878, p. 74. 



Ols. — The strongly marked umbonal ridge and the slightly 

 concave posterior slope at once mark this species as peculiar. 

 Two specimens in a moderately good state of preservation 

 have been forwarded; both have the entire shell removed, 

 and are therefore in the form of casts, but with the exception 

 of some slight displacement of the valves, the general out- 

 line is retained. I am inclined to doubt the reference of this 

 species to the genus Pleiirophorus made by Professor De 

 Koninck, although no doubt it departs considerably from the 

 true Pachydomoid type as exemplified by P. antiquatus and 

 P. globosus, the typical species. 



Loc. and Horizon. — Coral Creek, as before — (N'o. 102); 

 Bowen Eiver, at No. 25 Traverse Station (No. 136) ; Marine 

 Series. 



Collector. — E. L. Jack, Esq. 



