558 



CRUSTACEA. 



[OLE. PAI,. 



axis, and lateral segments directed 

 backward. Type O. nevadensis. 



PIG. 1035. Olenoides typicalis.; 



fordi, Walcott, 1887, Am. Jour. Sci. and 

 Arts, 3d ser., vol. 34, p. 195, Up.Taconic. 



hevis, Walcott, 1886, Bull. U.S. 

 Geo. Sur., No. 30, p. 187, Up. 

 Taconic. 



nevadensis, Meek, 1870, (Para- 

 doxides nevadensis,) Proc. 

 Acad. Nat. Sci. Phil., p. 62, 

 and Geol. Expl. 40th Par., 

 vol. 4, p. 23, Up. Taconic. 



quadriceps. Hall & Whitfield, 

 1877, (Dicellocephalus quad- 

 riceps,) Geol. Expl. 40th Par., 

 vol. 4, p. 240, Up. Taconic. 



spinosus, Walcott, 1885, (Ogygia spinosa,) 

 Mon. U. S. Geo. Sur., vol. 8, p. 63, Up. 

 Taconic. 



stissingensis, Dwight, 1889, Am. Jour. 

 Sci. and Arts, 3d ser., vol. 38, p. 147, 

 Up. Taconic. 



typicalis, Walcott, 1886, Bull. U. S. Geo. 

 Sur. No. 30, p. 183, Up. Taconic. 



wahsatchensis, Hall & Whitfield, 1877, 

 (Dicellocephalus wahsatchensis,) Geol. 

 Expl. 40th Par., vol. 4, p. 241, Up. Ta- 

 conic. 



Oknus, Dalman, 1826, Uber die Palseaden 

 oder die sogenannten Trilobiten, p. 54. 

 Not an American genus. 



f logani, see Loganellus quebecensis. 



thompsoni, see Elliptocephala thompsoni. 



undulostriatus, see Elliptocephala undu- 

 lostriata. 



vermonlana, see Mesonacis vermontana. 



ORYCTOCEPIIALUS, Walcott, 1886, Bull. U. S. 



Geo. Sur. No. 30, p. 210. [Ety. oryktos, 



furrowed ; kephale, head.] Glabella ob- 



long, transversely lobed; eyes central, 

 narrow, ocular ridges connecting them 

 with the axial furrow about the gla- 

 hella; facial suture marginal in front, 

 and cutting the posterior margin within 



i. Oryctocephalus primus, 

 shield. 



Cephalic 



with segmented 

 margin spinous. 



the postero-lateral angles ; free cheeks 

 spinous; pygidium 

 axis and pleural lobes 

 Type 0. primus, 

 primus, Walcott, 1886, 

 Bull. U. S. Geo. 

 Sur. No. 30, p. 210, 

 Up. Taconic. 

 PAL^OCARIS, Meek & 

 Worthen, 1865, 

 Proc. Acad. Nat. 

 Sci. Phil., p. 48. 

 [Ety palaio,,. an- 

 cient; fcam,shrimp.] 

 Inner and outer 

 pairs of antennae of nearly equal length' 



H'X 



FiQ. 1038. Palseocaris typus. 3 diam. 



the former each bearing a well devel- 

 oped accessory appendage; peduncles 

 of both pairs 

 shorter than 

 the flagella ; 

 head about 

 as long as the 

 first two ab- 

 dominal seg- 

 ments ; tho- 

 racic legs long 

 and slender, 

 anterior pair 

 not chelate ; 

 telson long, 



FIG. 1039 Paleeocaris typus. 

 Caudal part 4 diam. 



tapering, and 

 horizontally 

 flattened : sty- 

 lets with first joint very small, second 

 double, and also flattened horizontally. 

 Type P. typus. 



typus, Meek & Worthen, 1865, Proc. Acad. 

 Nat. Sci. Phil., p. 49, and Geo. Sur. 

 111., vol 2, p. 405, Coal Meas. 



