North American Palaeozoic Crustacea. 23 



Jonesl, Wetherby, 1881; Jour. Cinciunati Soc. Nat. Hist., vol. 4, p. 80, 



pi. 2, figs. 7, 7 a. Subcarboniferous. 



Leperditia (Isoc/uli/ia) minutissima, Hall, 1871 ; Desc. New Species Fossils 



Hudson River group, p. 7. Hudson River. 



Leperditia (hochilina) minutissima, Hall, 1872; 24tb Rept. New York State 



Mus. Nat. Hist., p. 231, pi. 8, fig. 13. 

 Leperditia (Isochilina) minutissima, Hall & Whitfield, 1873 ; Pal. Ohio, vol. 2, 



p. 102, pi. 4, fig. 4. 

 Leperditia (Isochilina) Ottawa, Jones, 1858 ; Annals & Mag. Nat. Hist., 2d series, 

 London, vol. 1, p. 248, pi. 10, fig. 1. Chazy. 



Leperditia {Isochilina) Ottawa, Jones, 1858; Geol. Survey Canada, Dec. 3, 

 p. 97, pi. 11, fig. 14. 

 Ottawa, Jones, 1884; Annals & Mag. Nat. Hist., 5th series, London, 

 vol. 14, p. 345. 

 Leaia, Jones, 1862 ; Mon. Fossil Estherise, p. 115. 



Gen. C/iar. — "'The carapace- valves are oblong; truncate behind, with a 

 slight curvature of outline ; boldly rounded in front ; either straight 

 or somewhat curved on the ventral border ; slightly on the dorsal edge ; 

 a slight umbo takes the place of the antero-dorsal angle, from whence 

 two conspicuous ridges (hollow within) pass along the surface of the 

 valve ; one directly across the valve to the antero-veutral angle ; the 

 other, and longer one, passes diagonally to the postero-ventral angle ; 

 these ridges divide the convexities of the valves in three, unequal, 

 triangular, smooth, sloping areas ; the anterior space is the smallest 

 and nearly semi-circular ; the middle one has its apex at the umbo, 

 and its base along the ventral margin ; and the posterior space is based 

 on the hinder margin, and reaches along the dorsal region to the umbo. 

 The surface of the valve is marked with 10-13 ? delicate ridges." . . . 

 (Jones, Mon. Fossil Estherise, p. 115. Type L. Leidyi, Lea.) 

 Cypricardia Leidyi, Lea, 1855 ; Proc. Acad. Nat. Sci. Phila., vol. 7, p. 341, pi. 4. 



Coal Measures. 

 Leidyi, Jones, 1862 ; Mon. Fossil Estherise, p. 116, pi. 5, figs. 11, 12. 

 Leidyi, Dawson, 1868; Acadian Geology, p. 256, fig. 78 c. 

 Leidyi, Packard, 1882 ; 12th Rept. U. S. Geol. Survey Territories, p. 358, 



fig. 24. 

 Leidyi, Jones, 1870; Geol. Mag., vol. 7, p. 219, pi. 9, fig. 11 ; also Geol. 



Mag., Dec. 3, vol. 1, p. 361, pi. 12, fig. 13. 

 tricariuata. Meek & Worthen, 1868 ; Geol. Survey Illinois, vol. 3, p. 541, 

 figs. Bj, Bg, Bg. Coal Measures, 



tricariuata. White, 1884 ; 13th Ann. Rept. Dept. Geol. Nat. Hist. Indiana, 

 p. 167, pi. 39, figs. 10-13. 

 Leperditia, Rouanlt, 1851 ; Bull. Soc. Geol. France, 2d series, vol. 8, p. 377. 

 Gen. Char. — Carapace inequivalved ; somewhat resembling a tamarind- 

 stone ; valves smooth, convex, nearly oblong, longer than broad, 

 inequilateral, posterior half broadest ; dorsal border straight ; basal 

 margin nearly semicircular. Anterior and posterior sides oblique 

 above, rounded below. Valves united along their dorsal borders by a 



