BIEDSEYE LIMESTONE. 41 



67. 2. MURCHISONIA? ANGUSTATA (n. ^.). 



Pl. X. Figs. 2 a, b. 



Subulate, elongated, narrow ; spire long, sharp ; volutions about nine or ten, rounded ; 

 suture simple ; aperture nearly circular ; surface 1 Length J to f of an inch. 



The form of this shell is well preserved in several specimens, but the surface is too much 

 eroded to define its markings. There is, in some specimens, obscure evidence of a carination 

 on the outside of a few of the lower whorls. 



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

 Phytopsis cellvlosum. 



68. 3. MURCHISONIA VENTRICOSA (n. *p.). 



Pl. X. Fig. 3. 



Conical, abruptly tapering ; breadth about half the length ; volutions about five, ventri- 

 cose, subangulated above, rapidly enlarging towards the aperture ; surface covered with 

 longitudinal arched threadlike striae, which, tending backwards from the suture, bend 

 forward after passing over the angle of the whorl. 



In the specimen under examination, the striae are only partially visible, except on the 

 upper part of the volutions : they are precisely like those on the species of Loxonema known 

 to me ; but the angular elevation along the upper part of the volution indicates that this 

 may be a species of Murchisonia, the Loxonema being destitute of such a carina. In the 

 cast, there is no evidence of the band marking the carina as in Murchisonia, but the striae 

 bend forward in the same manner on the lower part of the volutions. 



Position and locality. In the higher part of the rock, where it passes into the Trenton 

 limestone. Tribe's-hill, Mohawk valley. iState Collection.) 



69. 4. MURCHISONIA PER ANGUL ATA (n.*p.). 



Pu X. Fig. 4. 



Fusiform ; spire long, acute ; volutions rapidly diminishing in size, angular on the 

 middle, appressed above and below, except the last one, which is somewhat ventricose. 



There are some obscure traces of striae, and of the spiral band, which enables us to refer 

 the shell to the Genus Murchisonia, but it has been so much macerated as nearly to 

 obliterate these markings. The shell is readily recognized by the strongly angulated whorls, 

 which, above the lower one, are not ventricose. 



Position and locality. It occurs in a siliceous cherty mass of the Birdseye limestone, 

 associated with fragraenta of shells, corals, etc., near the upper termination of the rock. 

 Watertown, Jefierson county. (^''o'* Collection.) 



[ Pal.«ontology.] 6 



im 



