44 PALEONTOLOGY OF NEW-YORK. 



might be regarded as indicating distinct species, but a careful examination will decide them 

 to be identical. 



For further illustrations of this species, see Trenton limestone, Plate XXXVI. 



Position and locality. In the higher shaly and irregularly stratified portions of the Bird- 

 seye limestone, at Watertown, Jefferson county. {State Collection.) 



75. 8. PLEUROTOMARIA? NODULOSA (n. i'j^.). 



Pl. X. Fig. 10. 



Turbinate, spiral ; spire ascending, short, obtuse ; volutions few, angular, ventricose, 

 rapidly increasing towards the aperture ; umbilicus large ; surface marked by nodulose 

 spiral ridges, which are crossed by longitudinal lines, giving the shell a varicose appearance. 



Tlie surface of this shell, the characters of which are partially obliterated, somewhat 

 resembles Murchisonia varicosa ; but the spire is much shorter, and the last whorl larger 

 and more ventricose. The large deep umbilicus is also a distinguishing feature of this fossil. 



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

 Orthoceras multicameratum and Phytopsis. (State Collection.) 



76. 9. PLEUROTOMARIA? OBSOLETA (n. SJ9.). 



Pl. X. Fig. 11. 



Suborbicular, depressed-spiral ; volutions rounded, ventricose ; aperture round, with a 

 posterior depression which apparently communicates with the umbilicus ; umbilicus small ; 

 surface marked by longitudinal fine striae radiating from the umbilicus. 



Little more than a single volution of this specimen can be seen, the upper part of the 

 shell being enclosed in the rock. The margin of the aperture does not present the notch 

 characteristic of the Pleurotomaeia, and it is therefore referred with some doubt to that 

 genus. 



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

 preceding fossils. Watertown, Jefferson county. (State Collection.) 



77. 1. CYTHERINA {Species undetermined). 



Pl. X. Fig. 12. 



Broken- and separated valves of this little crustacean are of common occurrence in the 

 higher portions of the Birdseye limestone, though usually too imperfect for description. It 

 is probably identical with a species in the Trenton limestone, which will be described in 

 the proper place. 



Locality. Watertown, Jefferson county. (State Collection.) 



