170 
PALAEONTOLOGY OF NEW-YORK. 
218. 1. HOLOPEA SYMMETRICA ( n. sp.). 
Pl. XXXVII. Fig. 1. 
Spire conical, elevated, apex acute ; height much greater than the breadth ; volutions 
four or live, rounded, ventricose, increasing gradually from the apex ; surface marked 
with line crowded striae, which curve gently backwards from the sutures ; aperture nearly 
circular. 
This is a very pretty symmetrical shell, with the spire elevated and the volutions 
ventricose, resembling some species of Paludina. The striae are fine, close, and sometimes 
crowded together and elevated in fascia or undulations. All the specimens examined present 
the uniform character here given, and show scarcely a perceptible variation even in the 
size of the shell. 
Position and locality. In the upper crystalline portions of the limestone at Middleville. 
(State Collection.) 
219. 2. HOLOPEA OBLIQUA ( n. sp.) 
Pl. XXXVII. Figs. 2 a, b, c, d. 
Spiral, oblique, height and breadth nearly equal; spire very short, acute at the apex, 
composed of three or four volutions, diminishing rapidly above, the last one very ventricose; 
aperture somewhat circular, entire, transversely extended, with the outer lip thin ; surface 
smooth, or covered with line striae. 
This shell has heretofore been referred to the Genus Natica, from its general resemblance, 
though it is not probable that it is a true Natica. It is more oblique, and the spire is shorter 
and more abruptly acute than in either of the other species described. The aperture, in 
two specimens examined, is rounded upon the outer side, contracting towards its junction 
witU the body whorl. In the largest specimen seen, the surface is marked with vertical 
curving undulations or rounded ridges ; but these appear due to age, or other circumstances 
not constant in their influence, though something of the kind is obscurely visible in another 
specimen. The volutions are somewhat more appressed at their junction than the succeeding 
species. 
Fig. 2 a. View of the aperture of a small specimen. 
Fig. 2 b. View of the back of the shell. 
Fig. 2 c. Profile view of the same. 
Fig. 2 cl. Back of a larger specimen. 
Position and locality. This species occurs in the higher shaly part of the Trenton lime¬ 
stone at Middleville. The specimen fig. 2 d is from the upper crystalline portion of the 
rock at Watertown, Jefferson county. {State Collection.) 
