CRUSTACEA. 49 



[s.-g.J ODONTOCEPHALUS, Conrad. 1840. 

 Dalmanites (Odontocephalcs) selenurus. 



PLATE XI B, FIGS. 15-21; and PLATE XII, FIGS. 1-13. 



Asaiikus selenurus, Eaton. Geological Text Book, p. 31, pi. i. tig. 1. 1832 

 Calymenef odontocephala, Green. Monog. Trilotrites of North America, Suppl., p. 9. 1832. 

 Odontoeephalus selenurus, Conrad. Third Ann. Rept. Pala»ontological Dept. N. Y. Survey, p. 204. 1840 

 Odontocephalui selenurus, Vanuxem. Geology of N. Y., Survey Third Geol. Dist.. pp. 139, 140, tig. 1. 1842. 

 Odontoeephalus selenurus, Hall. Geologj i f V Y., Survey Fourth Geol. Dist.. p. 175, tig. 1. 1S43. 

 Dalmania selenurus, Hall. Twelfth Rept N ^ State Cab. Nat. Hist., p. 88. 1859. 

 Dalmania selenurus, Hall. Descr. New Species of Fossils, etc., p. 56. 1861. 

 Dalmania selenurus, Hall. Fifteenth Rept. N. Y. State Cab. Nat. Hist., p. 84. 1862. 



Odontoeephalus ? {Dalmanites (Odontoeephalus) arenarius, Meek and Wortheh. Geol. Surv. Illinois, 



vol. iii, pp. 416, 417. pi. ix. fig. 10. 

 Dalmanites selenurus, Hall. Illustrations of Devonian Fossils, pi. xii, figs. 12-14. 1S76. 

 Dalmanites JEgeria, Hall. Illustrations of Devonian Fossils, pi. xii, tigs. 1, 2, 7. 1n7U. 

 Dalmanites coronatus, Hall. Illustrations of Devonian Fossils, pi. xii, tigs. 15, 10. 1876. 



General Form and Proportions. Outline elliptical or elongate-sub-ovate ; 

 anterior and posterior margins ornate. Length somewhat less than twice 

 the width. 



Surface depressed-convex above, lateral slopes abrupt. Ceplfalon, thorax 

 and pygidium to one another in length as 1 to 1.3 to 1. 



Cephalon. Outline sub-semielliptical, somewhat produced in front; length 

 about one-half the width. Surface convex, sloping abruptly in front ami 

 at the sides. Border moderately broad, horizontal in front and composed of 

 nine conspicuous incisor-like processes, the strongest of which is central, 

 w r ith four on either side, which become regularly smaller as the margin nar- 

 rows backwards, the terminal one standing just in front of the lateral ex- 

 tremities of the frontal lobe of the glabella. These tooth-like extensions 

 are narrow and constricted at their bases, but widen rapidly so that they 

 come in contact at the outer margin, though remaining entirely discrete. On 

 the cheeks the border is broadly grooved and sloping, thickened along the 

 outer and inner boundaries, and at the genal angles rounded or produced 

 into a short, inconspicuous spinule. 



