CRUSTACEA— OSTRACOD A. 



341 



10. L. alta (Conrad). Siluric. 



Small, nearly symmetrical, strongly convex; length one and one 



half times height; eye tubercle pronounced, one fourth length of 



Fig. 1655. Leperditia satlaris, left and right valves, X 2. (After Grabau. ) 



valve from anterior end, and similar distance from dorsal line. 



Abundant in Manlius of New York, New Jersey, Pennsylvania, 

 etc. ; also in Lower Monroe of Ontario, Ohio, Michigan, etc. 



II. L. hudsonica Hall. (Fig. 1656, /-/i.) Devonic. 



Fig. 1656. a-c, Leperditella in/lata (5),* external and internal views of right valve, 

 end view, X 6; d^ e, Leperditia ccBcigena (7), right valve and end view, enlarged ; 

 f-h, L. hudsonica (li), right valve and profiles, X ^5 ; i-k^ hochilina subnodosa 

 (12), X I 5 ^~^» I. jonesi (13), left valve, X Yz 5 ^~^i Schviidtella crassimarginata 

 (16), right valve, X ^ ; r-t, S. umbonata (17), left, end, and interior of right valve, 

 X 14- {f-^i after Jones, the others after Ulrich. ) 



* The numbers following names in parenthesis refer to the number preceding the 

 species in the text. 



Very small, deeply convex ; hinge proportionately long ; anterior 

 cardinal angle nearly a rectangle ; eye tubercle faint or wantmg. 

 Hamilton of New York. 



V. IsociiiLiNA Jones. 

 Like Leperditia, except that the valves do not overlap, but are 

 equal in every respect. Surface sometimes lobulate or nodose. 



