GASTEROPODA OF THE LOWER GREEN MARLS. 171 
stance of a Plagiostoma or Dianchora, and probably numbered 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 structure, 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, 2d ser., p. 389. 
Pl. txvu, 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 borealis 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. 
