BLACK-RIVER LIMESTONE. 
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92. 1. ENDOCERAS SUBCENTRALE (n. sp.). 
Pl. XVII. Fig. 4. 
External form unknown, much elongated ; septa rather distant; siphuncle a large 
straight subcentral tube, with external imbricating elevations at the attachment of the septa. 
The septa, on approaching the side of the siphuncle, turn suddenly upwards, or towards 
the apex, before joining the tube. A small portion only of the internal tube is visible, but 
enough remains to show its character. The marking is too faint to be traced, but it probably 
differs from any other species in this rock. 
Position and locality. This fossil occurs, associated with the Ormoceras, in the limestone 
of Black river, at Watertown, Jefferson county. (State Collection.) 
93. 2. ENDOCERAS LONGISSIMUM ( n. sp .). 
Pl. XVIII. Figs. 
Extremely elongated, cylindrical. In the specimen before us, the internal embryo tubes 
of the siphuncle, only, are preserved : these are cylindrical, elongated, very gradually 
tapering, each one fitting within the other nearly close at the aperture, but receding from 
each other towards the smaller extremity ; markings of the surface not visible. 
The section 1 a shows at least three distinct tubes, one within the other, which extend 
the whole length of the specimen. The portion figured is eighteen inches in length, and 
this is probably much less than half the whole length of the original. Fragments of this 
species are very abundant at Watertown, and they are often found embraced within portions 
of the original shell, which was at least six inches in diameter and several feet in length. 
The two figures connected by a dotted line are parts of the same specimen, joining as 
indicated. The section 1 a shows the different tubes, one within the other. 
Position and locality. In the Black-river limestone, associated with Ormoceras. Water- 
town, Jefferson county. (Cabinet of the Albany Institute.) 
94. 3. ENDOCERAS MULTITUBULATUM {n. sp.). 
Pl. XVIII. Figs. 2 a, b. 
Teretely conical, tapering somewhat rapidly; embryo sheaths numerous ( five), one 
within the other ; sheaths thin, smooth externally ; interspaces equal, narrow. 
This species differs from the last, in tapering more rapidly towards the apex, and in the 
consequently different form, as well as in the greater number of sheaths, which latter, 
however, would not be regarded as important. 
Position and locality. In the Black-river limestone at Watertown, Jefferson county, 
associated with those forms previously figured. 
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