18 



North American Palaeozoic Crustacea. 



snblevis, Packard, 1882; Am. Naturalist, p. 952, fig. 11. 



snbhpvis, Packard, 1883; 12th Rept. U. S. Geol. Survey Terr., p. 450, 



fig. 71b. 

 sublevis, Beecher, 1884; 2d Geol. Survey Peiina., vol. PPP, p. 5. 

 subljEvis, Jones & Woodward, 1884; Geol. Mag., Dec. 3, vol. 1, p. 2, 



pi. 13, figs. 3, 4, 5. 

 subL-evis, Etheridge, Woodward & .Jones, ISSf) ; 3d Rept. Comm. Fossil 



Phyllopoda Pal. Rocks, p. 35. 

 sublfevis. Hall & Clarke, 1888; Pal. New York, vol. 7, p. 17(j, pi. 29, 



figs. 11-13. 

 sublevis, Etheridge, W'oodward & .Jones, 1888 ; 6th Rept. Comm. Foss, 



Phyllopoda, p. 8. 

 Whitfieldi, Clarke, 1885 ; Bull. U. S. Geol, Survey, No. 16, p. 45, pi. 2, 

 figs. 3, 4. Portage, 



Whitfieldi, Hall & Clarke, 1888; Pal. New York, vol. 7, p. 172, pi. 29, 



figs. 20, 21. 

 Whitfieldi, Etheridge, Woodward & Jones, 1888 ; 6th Rept. Comm. Foss. 

 Phyllopoda, p. S. 

 Echinognathus, Walcott, 1882; Am. Jour, Sci., 3d series, vol. 23, p. 213. 

 (Jill. Char. — Endognathary limbs (one or more pairs) formed of 8 or 9 

 joints, 6 of which carry long backward-curving spines articulated to 

 their posterior side. Terminal joint slender, elongate, acuminate. 

 Surface of the body, and larger joints of the cephalic appendage orna- 

 mented with scale-like markings as in the genus Pterygotas. Type 

 E. Clevelandi (Walcott, Am. Jour. Sci., 3d series, vol. 23). 

 Clevelandi, Walcott, 1882 ; Am. Jour. Sci., 3d series, vol. 23, p. 213, 

 figs. 1, 2. Utica Slates. 



Eurypterus ? Clevelandi, Walcott, 1882 ; Am. Jour. Sci., 3d series, vol. 23, 

 p. 151. 

 Elymocaris, Beecher, 1884 ; 2d Geol. Survey Pennsylvania, vol. PPP, p. 13. 



Diagnosis. — Carapace bivalvular, hinge-line straight 

 and extending nearly the entire length of the 

 valves. Outline elongat.e-subquadrangular or sub- 

 ovate. Surface gently and evenly convex. Cei)lialic 

 region smootli or marked by two low broad nodes ; 

 optic node usually distinct. Rostrum absent or 

 not observed. Abdomen composed of 2 naked seg- 

 ments. Post-abdomen Avith a very short caudal 

 plate to which are articulated a broad, convex, 

 and rapidly tapering telson, and two short lateral 

 spines, which are crenulated along their inner 

 margins for the attachment of the seta^. (Hall & 

 Clarke, Pal. New York, vol. 7, p. Iv.) 

 capsella, Hall & Clarke, 1888 ; Pal. New York, vol. 7, p. 181, pi. 31, fig. 4. 



Hamilton. 



ailiqua, Beecher, 1884; 2d Geol. Survey Pennsylvania, vol. PPP, p. 13, 



pi. 2, figs. 1, 2. Chemung. 



