GASTEROPODA OP THE LOWER GREEN MARLS. 171 



stance of a Plagiostoma or Dianchora, and probably nnmbered more than 

 two on the shell when living, as there are remains of smaller specimens 

 besides the two of large growth. The shells are mostly exfoliated and show 

 a strongly lamellose stnicture, as if made up of a succession of layers one 

 over the other from the inside. Where broken through they are of consid- 

 erable thickness, and in this respect differ from the type specimens as 

 described by Mr. Conrad as fragile. It may be that I have wrongly iden- 

 tified the specimens, but the similarity between them is so great that I have 

 not felt safe in considering them as distinct from Conrad's species. 



Formation and locality: In the blackish layers of the Lower Marl Beds, 

 at Crosswicks Creek, New Jersey. 



Extra limita. 



Neptunea impressa Gabb: Jour. Acad. Nat. Sci., Phila., vol. 4, 3d ser., p. 389. 

 PL Lxviii, Fig. 5. 



This species was described by Mr. Gabb, from Hardeman County, 

 Tennessee, from the Ripley group, and cited in his synopsis of the Creta- 

 ceous formations as coming from New Jersey (see p. 62). I have not seen 

 among the casts from New Jersey any one which could reasonably be con- 

 sidered as identical with the specimen which Mr. Gabb has figured. 



Anisomyon borealis=Hipponyx horealis Mort. See Gabb's Synopsis Cret. Foss., 

 p. 38. 



I can find no other evidence of this species having been found in New 

 Jersey than the reference in Mr. Gabb's synopsis. It has probably occurred 

 by mistake in looking at Dr. Morton's original description, where he men- 

 tions having described another species of the genus Hipponyx from New 

 Jersey. 



