186 PALHONTOLOGY OF NEW-YORK. 
243. 3. BUCANIA EXPANSA (xn. sp.). 
PL. XL. Figs. 7 a, b'c, d. 
Convolute, trumpet-shaped ; volutions three or four, subangular, the last one elongated, 
rapidly enlarging and abruptly expanded at the aperture ; aperture broadly semicircular 
or sublunate, with a sinus at the dorsal side ; dorsal line obtusely carinated ; section of the 
last volution, below the aperture, subtriangular ; of the inner volutions, subelliptical, with 
the extremities obtusely angular ; original surface striated. Specimen a cast. 
This shell is not unlike Bellerophon cornuarietis (Sowrrsy, Min. Conchology, tab. 469, 
fig. 2); but the volutions in that species are represented as not contiguous. The species 
under consideration differs from either of the two preceding in a very obvious manner. 
The broadly expanded aperture and obtuse carina of the last volution are prominent 
features ; and in fragments, the subtriangular form of sections of the last volution are often 
sufficient to enable us to identify the species. The strongly marked carina commences at 
the base of the last volution, and continues to the aperture. The volutions are closely 
pressed against each other, the convex dorsal side producing a corresponding depression on 
the ventral side of the contiguous volution. 
Fig. 7 a. View of the back of the shell, showing the strong carina, expanded aperture, and sinus on the 
dorsal margin. 06. Lateral view of the same. 
Fig. 7 c. Transverse section of the last volution, below the aperture. 
Fig. 7 d, e. Lateral and front view of another specimen, from which the expanded portion of the aper- 
ture is broken off, and showing also a little deviation in form. 
Position and locality. In the lower irregularly bedded portions of the Trenton limestone, 
and in the strata resting on the Black-river limestone, at Watertown, Jefferson county. 
(State Collection.) 
244. 4. BUCANIA BIDORSATA (xn. sp.). 
Pu. XL. Figs. 8 a, b,c, d, e, f, g. 
Convolute, subglobose, with a deep umbilicus; volutions about three, the last one 
extended and somewhat straight, gradually enlarging and more abruptly expanding to- 
wards the aperture ; dorsal margin with a double or grooved carina, on the centre of which 
is a narrow elevated line; on each side of the dorsal band is a broad groove or depression, 
and an obtusely angular ridge, the latter being half way between the centre and margin 
of the shell; surface ornamented by transverse filiform strie, which, receding from the 
umbilicus, bend abruptly backwards near the centre, making a more gentle curve on the 
dorsal band ; aperture sublunate. 
In young specimens, the carinal band is very conspicuous, with a narrow elevated 
central line. The lateral carine or ridges scarcely affect the direction of the strie; the 
depressions on the outside of these are less conspicuous than on the inner side. In this 
respect, however, there is some variation in specimens from different localities. In casts of 
