GASTEROPODA OF THE LOWER GREEN MARLS. 99 
acters, seems to be a very necessary one, and to fill a place, or at least 
to offer a place for the arrangement of several species of casts of the 
New Jersey Cretaceous, which would otherwise be left doubtful, and for 
which there seems to be no other place unless Jphinw of Adams is the same. 
They bear some slight resemblance in form to what would be produced by 
internal casts of Rhizocheilus, but the umbilical opening is larger and the 
base of the aperture less prolonged than would be the case by any of those 
of that genus which I have seen. The general form of the cast would 
readily indicate a position for them near Cancellaria, but the absence of the 
columellar folds renders it doubtful until that of the 7. /Tilgardi and T. Con- 
radi herein described is seen, which at once removes all doubt. Mr. Gabb 
seems to have been very doubtful of the generic relations of these shells, 
and referred the type species at one time to Cancellaria, and subsequently 
considered it as related to Ninella of Gray, from which it must be very dis- 
tinct. He, subsequent to these references (in his Synopsis and in the Proe. 
Acad. Nat. Sci., Phila., in 1861, p. 321), reconsidered the subject and con- 
cluded the genus was a good one (Proc. Acad. Nat. Sei., Phila., 1876, p. 
300), and states that he thinks it “not remote from Trichotropis.” Dr. 
Stoliezka in Ind. Geol. Surv. Pal. Indica, Cret. Fauna, South Ind., vol. 1, pp. 
161, 162, remarks that the genus ought to be separated from Cancellaria if 
it has but one columellar fold, but the casts often show no evidence of any 
fold, as above stated. He also observes that the presence of spiral striz 
and the absence of transverse (vertical) ribs indicate a different style of 
surface structure from that usually shown in the Cancellariide, and thinks it 
probable these shells may belong to the ‘“ Trochide or Littorinide (Modu- 
lus).” They much resemble Modulus in character except for their gieater 
elevation, but the New Jersey casts mostly show remains of vertical or 
transverse folds, showing their closer relations to Cancellaria than he had 
supposed. The specimens which I have considered as identical with 7. 
Hilgardi, Conrad's type of the genus, show unmistakable evidence of ver- 
tical folds. In view of all these resemblances I consider them most nearly 
related to Cancellaria. There is only one other alternative to this conclu- 
sion, and that is in the genus [phinw Adams, which Chenu and Tryon arrange 
under the Trichotropide. The casts of this shell would present almost 
