167 



MUBCHISONIA ESTELLA. (N. Sp.) 

 Fig. 139. 



Description, — Spire very acutely conical, elongated, slender, screw- 

 shaped ; whorls numerous, angulated a little below the middle ; above the 

 angular edge descending with a flat or slightly concave slope about two 

 thirds the distance to the suture, just before reaching which there is a 

 barely perceptible convexity; suture deep. Below the angulation the 

 slope is flat all the way to the suture. The angular edge is apparently 

 sharp, and if there be a band it must be a very narrow one. 



A fragment consisting of 15 whorls is 18 lines in length ; 5J lines wide 

 at the larger and 1 line at the smaller extremity. Another specimen con- 

 sisting also of 15 whorls is 17 lines in length, 5J lines at the larger and 

 1 line at the smaller extremity. The dimensions of these two (the only 

 ones collected) are therefore the same. The angulation is situated a 

 little above the lower third of the length of the whorls. 



This species is allied to M. longispira (Hall), Pal. N. Y., Vol. 2, 

 p. 345, PI. 83, Pig. 2, a, but is more acutely angular in the whorls. 



Locality and Formation. — Gait. In the Gruelph formation ; Middle 

 Silurian. 



Collectors.— E. Billings, E. Bell. 



MURCHISONIA MtLITTA. (N. Sp.) 



Pig. 140. 



Fig. 141. 



Fig. 140. — Murchisonia Mylitta. 



141. — M. Hercyna. 



142. — Holopea Harmonia. 



Pig. 142. 



Description. — Shell short; whorls 4 or 5, ventricose, with a narrow 

 spiral band a Uttle above the middle on the last. Above the band the 



