157 



MUKCHISONIA ESTELLA. (N. gp.) 

 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 ; 5 J 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, Fig. 2, #, but is more acutely angular in the whorls. 



Locality and Formation. Gait. In the Guelph formation ; Middle 

 Silurian. 



Collectors. E. Billings, R. BeU. 



MURCHISONIA MYLITTA. (N. sp.) 



Fig. 140. 



Fig. 142. 



Fig. 141. 



Fig. 140. Murchisonia Mylitta. 



141. M. Hercyna. 



142. Holopea Harmonia. 



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

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



