32 



Pleukotomaria Amphitrite. (N.^sp.) 



Desei-iption. — Shell very large, trochoid, conical, with a flat base. The 

 specimen consists of the body whorl and a portion of the one next above it. 

 Although imperfect there is suiScent to shew that this is a smoothly conical 

 fla1>based species belonging to that group of which P. Bamsayi of the 

 Calciferous formation is an example. The basal margin is narrowly rounded, 

 the lower side of the body whorl flat and at a right angle (or very nearly 

 so, to the vertical axis of the shell. The upper side of the whorl is gently 

 convex, or nearly flat for a short distance from the aperture and then gra- 

 dually becomes gently concave. Judging from this form, the spire is most 

 probably an uniformly tapering cone. As the lower side of the body whorl 

 forms an angle of about 60° with the upper side the apical angle would 

 also be about 60°. There is evidence of a wide umbilicus. 



Surface with fine crowded sublameUose striae curving backwards so as 

 to form an acute angle in passing over the margin. Width of the base 4 

 inches. 



This fine shell is allied to P. Ramsayi, but is nearly four times as wide 

 at the base. 



Localifii and Formation. — South point of Large Island, Mingan 

 Islands. Chazy or Black River. 



Collector. — J. Richardson. « 



Mtjrchisonia Vesta. (N. sp.) 



Fig. 33. 

 Fig. 33. — Murchisonia Vesta. 



BeKcription. — Elongate, acutely conical, apical angle apparently from 

 20° to yO° whorls from six to nine, moderately ventricose with an incon- 

 spicuous flat spiral band a little below the middle. Surface with fine 

 striae in the upper part of the whorl curving backwards to the spiral band 

 and in the lower part curving forwards. 



The largest specimen seen is a fragment consisting of three whorls IJ 

 inches in length, apparently belonging to an individual which if complete 

 would be about 2| inches in length ; width of spiral band about 1 line ; 

 fragments of smaller individuals are common. 



