526 Contributions to Invertebrate Palseontology. 



striae if they had ever existed ; but no remains of them are visible 

 at present. 



Formation and Locality. — In the white cherty layers of the 

 Upper Helderberg group, near Dublin, Ohio. 



Genus I^OXOjVEMA Phillips. 

 L.o:x:ouenia parTulum. 



Plate VII, fig. 5. 



Loxonema parvulum Wliitf., Ann. N. Y. Acad. Sci., Alarch, 1882, p. 204. 



Shell minute, scarcely exceeding a fourth of an inch in length, and propor- 

 tionally slender, with a rapidly ascending spire, which is slightly more rapidly 

 tapering in the upper than in the lower part. Volutions six or six and a half, 

 moderately convex on the outer surface, and more strongly rounded on the 

 lower part of the exposed portion than on the upper ; suture-line distinct, but 

 not margined by a flattening of the upper edge of the succeeding volution. 

 Aperture elongate, slightly angular at the base, and pointed above. Surface 

 of the volutions marked by a large number of distinct vertical striae, which 

 are more numerous and slightly finer on the body volution than above, and are 

 so nearly destitute of sigmoid curvature as to ai>pear vertical iintil closely ex- 

 amined. 



The small size of the shell, the nearly vertical lines, and the un- 

 equally expanding volutions, are distinguishing features ; the latter 

 character, however, appears to vary a little in degree on some of 

 the specimens. It will be readily distinguished from the young 

 shells of L. Hamiltonise, which occurs in the same rock, by the 

 number of volutions and the slender form. 



Formation and Locality. — In the white cherty layers of the 

 Upper Helderberg limestone, near Dublin, Ohio. 



CEPHALOPODA. 



Genus ORTHOCERAS Breyn. 



Ortlioceras iitintiiiiu. 



Plate VII, figs. 1 and 2. 



Orthoceras nuntium Hall, 15th Rept. State Cab., p. 79, pi. 8, figs. 3 and 4. Pal. 

 N. Y., must. Dev. Foss., p. 43, figs. 4 and 15. 



Comp. 0. suhulatum Hall, Geol. Rept. 4tli Dist. N. Y., p. 180, fig., and Pal. N. Y. 

 Illust. Dev. Foss., pi. 38 ; also 0. Thoas and 0. Uyas Hall, of same work. 



Shell attaining considerable size, the specimen used for description and 

 figured having a length of nine inches, and still imperfect at both extremities, 

 retains only about an inch of the outer chamber, and has a diameter of half 



