42 PALEONTOLOGY OF NEW-YORK. 



70. 5. MURCHIS0NIA1 VARICOSA («.*;>.). 



Pi. X. Figs. 7 a, b. 



Turreted, or ovoidly conical ; volutions rapidly diminishing, angular, ventricose ; surface 

 marked with longitudinal ribs or strong striae, which are crossed by transverse ridges, giving 

 it a varicose appearance. 



The specimens which I have seen are obscure from the adhesion of stony matter, but 

 the species seems well characterized and easily recognized, and it is therefore given in its 

 imperfect condition. The lower volutions bear about two or three prominent ridges or 

 angular elevations upon the upper side, while they are more regularly rounded below. 



Fig. 7 a. A specimen having the surface much worn and weathered ; the markings are but partially 



visible. 

 Fig. 7 b. Longitudinal section of a specimen of the same shell. 



PosUion and locality. This species occurs in the upper part of the Birdseye limestone, 

 associated with Phytopsis and the preceding species of shells. It also occurs in the Black- 

 river limestone, near its upper termination. Watertown, Jefferson county. 



71. 1. NATICA? {Species undetermined) . 



Pl. X. Fig. 5. 

 Volutions about four, rapidly enlarging from the apex, last one very ventricose ; surface 

 smooth 1 ; suture apparently channelled ; spire but little elevated. 



This small shell is of rare occurrence in this rock, and I am by no means satisfied that it 

 is distinct from a species of the Trenton limestone. It will be readily recognized from the 

 figure. 



Position and locality. In the upper part of the Birdseye limestone, associated with 

 Pleurotomaria, Phytopsis, and other fossils. Watertown, Jefferson county. 



72. 5. PLEUROTOMARIA 1 NUCLEOL AT A («.«;).). 



Pu X. Fig. 6. 

 Trochiform ; spire short, rapidly tapering to an obtuse termination ; volutions few, 

 angular, flat above, the last one ventricose below ; suture canaliculate. 



The last volution composes nearly the entire shell, the upper ones being very small, and 

 somewhat depressed. This is a small distinct species, which I have observed in no other 

 position. 



Fig. 6 a. Natural size of specimen. 

 Fig. 6 b. Enlarged view of the same. 



Position and locality. In tlie upper part of the Birdseye limestone, with the last species. 

 Watertown, Jefferson county. 



