eh 



580 Professor Emerson on HaWs Geological Collections. 



A small fragment of gray argillaceous limestone was filled with specimens 



of this species, mostly as single valves and without admixture of other forms. 



The cleavage face of the rock showed many valves much 



weathered, the color being lost and the surface rough. They 



agree with the L. alta of the Tentaculite limestone. A few 



5 ^ ^ valves slightly larger occur in a second fragment of a lime- 



Fig. 5 a, left valve x 4; ,.,,,»■., .i, r. -i /. 



fi"-.5 6 cross-section from stone like the first, Dut With fossils of many species, espe- 



polislied section. cially Entomostraca, it having furnished all the species 



of that class described below, besides three species of Brachiopoda. 

 North shore Frobisher Bay. 



Leperditia canadensis, Jones. 



1858. Lejierditia canadensis, Jones. An. and Mag. Nat. Hist. 3d ser. i, p. 244, pi. ix, f. 11-15. 



Carapace valve minute, mottled brown, uniformly convex, convexity greatest 

 in the anterior third, eye tubercle well marked, nuchal de- 

 pression sloping equally to dorsal and ventral border. 

 Dorsal margin straight, shorter than gTeatest length, 

 ,,. °" . 1 , , , ^ ventral margin obliquelv convex, extremities unequal, 



Fig. 6 «, right valve, x4; fig. o i ^ j 17 



6 6, surface, X 80. Length, anterior angular, posterior broadly rounded. Surface of 

 If mm. ; breadth, If mm. y^ive covcred with fine irregularly placed pustules in the 

 specimen figured, in another coarsely and irregularly pitted. The small size and 

 the pustulose surface do not agree with the published descriptions of L. cana- 

 densis, but the fine hair like ])ustules, visible only with high magnifying power, 

 would generally be wanting, the other valves in the same piece of stone showing 

 no trace thereof. 



The specimen figured in a small piece of buff limestone from the north side 

 of Frobisher Bay 5 other valves in the gray limestone already mentioned. 



Peimitia muta, Jones. 



1858. Ct/theropais concinua, Jones. ? An. and Mag. of Nat. Hist. 3d ser„ vol. i, p. 252, pi. 9, f. B. 

 1865. FrimUia muta, Jones. Ibid. vol. xvi, p. 425. 



Carapace- valve minute, smooth and shining ; deep chestnut brown ; in weath- 

 ered specimens dead white; ovate to oblong-ovate; generally leper- 

 , ditia-shaped in outline, hinge-line straight, ends very unequal, ven- 



Fig. 7 left valve ^^'^^ edge curved. Occurs in great abundance in company with the 

 magnified four other entomostraca described, and alone in several small pieces of 

 buff limestone. One piece labeled north shore Frobisher Bay, the 

 others without special labels. Forms agreeing with the P. concinua, Jones, from 

 the Canadian Trenton, as also with the elongate P. tenera, Linnarsson (Vester- 



