tXICA SLATE AND HUDSON-RIVER GROUP. 311 



371. 18. ENDOCERAS PROTEIFORME 1 



Pi,. LXXXV. Fig9. 1 a -/. 

 Reference pag. 208 - 216, pi. 45 - 50, of this volume. 



This species, which is apparently identical with H. proteiforme of the Trenton limestone, 

 is abundant in the Utica slate in many localities. It presents some deviations from the 

 prevailing varieties in the Trenton limestone, but not greater than is observed in some 

 specimens in that rock. In the small specimens, which are more common than any others, 

 the distance of the septa is from one fourth to one third of the diameter, and the siphuncle 

 is small and slightly excenlric. I have never found them in this rock enclosed in larger 

 tubes or embryo sheaths. The specimens are usually casts in sulphuret of iron, and very 

 perfectly preserved ; they are often compressed, and the section is elliptical ; but this 

 feature is always due to pressure. The siphuncle likewise shows slight deviations from its 

 prevailing position, and it is often so nearly central that the difference escapes observation. 



Fig. 1 a. A specimen presi^rving a large part of the outer chamber. The longitudinal groove is due to 

 pressure which has broken the shell, the broken edges curving inwards. 



Figs. 1 i, c. Specimens of the smaller extremity of the fossil. 



The septa in fig. I b, show a slight arching upwards, but this is not a usual character. 



Fig. \ d. A fragment and sections of the two extremities, showing an elliptical form, which is due to 

 pressure. 



Fig. 1 e. A similar smaller fragment of the same form. 



Fig. 1 /. A smaller fragment, with sections circular. 



The elliptical forms are variable in their degree of eccentricity, and the apparent position 

 of the siphuncle is often influenced by the same cause. 



Position and locality. This species is abundant in the black slate at Turin, in Lewis 

 county ; it is likewise foimd at Canajoharie ; on the Oxtungo creek, above Fort-Plain, and 

 in other places in the Mohawk valley. (State Collection.) 



372. 26. ORTHOCERAS {Species undetermined). 

 Pi.. LXXXV. Fig. 2. 



This is a crushed specimen, slightly folded inwards along the centre, and preserving the 

 shell along this line. The original shell is preserved on other parts of the specimen, but 

 all the surface markings are obliterated. The proportional distance of the septa is much 

 greater than in the preceding species, and the character of the specimen is otherwise 

 unlike that of the previous one. 



Position and locality. In the Utica slate at Turin, Lewis county. 



