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. sp.). 
Pu. 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. 
The 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 (x. sp.). 
Pu. 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 strie 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 PLEURoTomaria, 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 
Pu. X. Fig. 12, 
( Species undetermined ) . 
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.) 
