CEPHALOPODA. 
37 
siphuncular significance. In other characters it resembles some described 
species of gastropoda belonging to the genus Porcellia ; but with the present 
material it is difficult to make a satisfactory determination. 
The specimen illustrated shows three volutions and measures 100 mm. in 
greatest diameter. 
Distribution. In the sandstones of the Waverly group, Warren county, Pa, 
TrOCHOCERAS ? (GoNIOCERAS ?) PANDUM. 
PLATE CXVII, FIGS. 3-5. 
Trochoceras f {Gonloceras?) pandtim, Hall. Pal. N. A"., vol. v, pt. 2, p. 403, pi. ill, tig-. 4. 1879. 
No additional specimens of this species have been obtained since the original 
publication in 1879, and its generic relations are still uncertain. In addition 
to its comparison with some associated forms of Trochoceras from the Schoharie 
grit, as noticed in Pal. N. Y,, vol. v, pt. 2, p. 403, it may also be compared 
with Gomphoceras fax, illustrated on plate cxxii. 
NAUTILUS, Breynius. 1732. 
Nautilus oriens. 
PLATE CXXVI, FIG. 2. 
Nautilus orievs. Hall. Pal. N. Y., vol. v, pt. 2, p. 420. 1879. 
Nautilus Hyatti. 
PLATE CXXVI, PIG. 1. 
Nautilus Hyatti, Hall. Fifth Ann. Kept. State Geologist. Expl. xil. (126) 11, fig. 1. 1886. 
In its general characters, this species is closely related to N. bucinum (Pal. N. 
Y., vol. V, pt. 2, p, 412). The shell is more rapidly expanded than in that 
species, especially toward the apex. The volutions are free. The transverse 
section is sub-circular in the apical portion of the shell, broadly oval through the 
chamber of habitation, a,nd with no dorsal sinus produced by the contiguity of 
the volutions as in N. bucinum. 
The specimen is an external mould preserved in an argillaceous concretion, 
and the form and surface characters of the shell are well preserved. The sur- 
