BLACK-RIVER LIMESTONE. 
53 
Plate XIII. 
Fig. 1. Lateral view of a specimen. A part of the last volution, near the aperture, is broken off] 
Fig. 1 a. Lateral view of the cast of a smaller specimen. 
Fig. I b. Dorsal view of the same specimen. 
Fig. 3. A section apparently of the same fossil, though the surface markings are not preserved. The 
septa are distinctly shown in a portion of the shell, and the dorsal siphon at two points a, a. 
I have not been able to ascertain positively the position of the siphon in the other specimens 
hearing the shell, figs. I and 1 a. 
Plate XIII. (bis). 
Fig. 1. A large specimen, showing a part of the fossil denuded of the shell, the direction and distance 
of the septa, and a portion of the deep outer chamber, the extremity being broken off 
I am indebted to Dr. Crawe for the use of this fine specimen, as well as for that on 
Plate XIII. fig. 1. 
Position and locality. This fossil is known to me only as occurring at Watertown, Jef¬ 
ferson county, in the Black-river (or u seven-foot tier” of) limestone, being unknown in 
any higher position, ( State Collection.) 
€ 
87. 2. LITUITES CONVOLVANS? 
Pl. XIII. Figs. 2, 2 a. 
Compare Lituites convolvans. Hisinger, Pet. Suecica, 1837, pag. 27, pl. 8, fig. 6; Anteckn V. tab. v. fig. 1, 2. 
Lituites imperfectus. Wahlenberg, Nov. Act. Reg. Soc. Sci. Upsal, 1821. 
Convolute, discoidal, gradually enlarging ; volutions about two or three, scarcely con¬ 
tiguous, outer one separating and continued in a direct line towards the aperture ; surface 
smooth'?; section circular; septa plain, moderately concave, direction oblicjue from the 
inner side of the volution outward and upwards ; siphuncle dorsal 1 ? 
Two or three specimens of this species have been discovered, where exposed upon the 
weathered surface of the limestone, which is too compact to allow of separating perfect 
specimens. So far as can be determined, the surface is smooth and the section circular. It 
is evidently closely allied to the L. convolvans ut supra, and probably identical with that 
fossil, which is found in the older limestone of Sweden. 
Fig. 2. A portion of a cast, showing the septa and part of the outer chamber. 
Fig. 2 a. A vertical section of another individual as seen on the weathered surface of the limestone, 
showing the septa, which are removed from the smaller extremity by weathering. The cast 
is worn down below the siphuncle, which has not been observed in any specimen yet seen. 
Position and locality. In the Black-river limestone, associated with large numbers of 
Orthocerata. Watertown, Jefferson county. 
