558 



CRUSTACEA. 



[OIvE. — PAI,. 



axis, and lateral segments directed 

 backward. Type 0. nevadensis. 



Fig. 1035.— Olenoides typicalis.J 



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

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



kevis, 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, t 

 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. 

 Olenus, Dalman, 1826, Uber die Palaeaden 

 oder die sogenannten Trilobiten, p. 54. 

 Not an American genus. 



f logani, see Loganellus quebecensis. 



thompsoni, see Elliptocephala thompsoni. 



undulostriatus, see Elliptocephala undu- 

 lostriata. 



vermontana, see Mesonacis vermontana. 



Okyctocephalus, 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- 

 bella ; facial suture marginal in front, 

 and cutting the posterior margin within 



primus. Cephalic 



Fig.» 1036.— Oryctocephnlus 

 shield. 



the postero-lateral angles ; free cheeks 

 spinous; pygidium with segmented 

 axis and pleural lobes ; margin spinous. 

 Type O. primus, 

 primus, Walcott, 1886, 

 Bull. U. S. Geo. 

 Sur. No. 30, p. 210, 

 Up. Taconic. 

 PaljEocaris, Meek & 

 Worthen, 1865, 



Proc. Acad. Nat. 

 Sci. Phil., p. 48. 

 [Ety. palaios, an 

 cient; fcam,shrimp.] 

 Inner and outer 

 pairs of antenna' of nearly equal length' 



Fig 



1037. — Orycto- 

 cepbalus primus. 

 Pygidium. 



Fig. 1038.— Pal seocaris typus. 3 diam. 



the former each bearing a well devel- 

 oped accossory 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, 

 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. 



Fig. 1039— Palseocaris typus. 

 Caudal part 4 diam. 



