PACK.\.RD.] 



THE ORDER PHYLLOCARIDA. 



451 



E. armahts (Hall) ^=E. punctatus (Hall), Hamilton gro.np, Devonian, New York. 

 E. pusttilosus Whittield, 1. o. 38, Erie shales, Devonian. Ohio. 

 E. mtdtimdosus Whittield, 1. c. Z-i, Erie shales, Devonian. Ohio. 



Genus Discinocaris Woodward, 1866. 



Like the upper valve of a Discina, but with a wedge-shaped opening 

 which cuts the disk nearly to its center. 



D. iroumiana Woodward, Proc. Geol. Soc. 502, 1866. 



Genus Spathiocaris Clarke, 1882. 



Differs from Biscinocans in the presence of 

 the "rostrum" or plate acting as another valve 

 to cover the cleft, and also in its more nearly 

 circular outline (Clarke). 

 S, emersonii Clarke, Amer. Jour. Sc. sxiii, 477, June, 1882. 



Genus Lisgocaris Clarke. 



Fig. 71 A. — Echinocaris inulti- 

 nodosus. After Whitfield. 



Carapace in one piece, without evidence of 

 dorsal suture. Periphery subpentagonal, lateral 

 edges parallel, making sbarp angles with the 

 two anterior edges, which are re-entrantly curved, 

 and meet in the axis of the carapace. As in ^. ^ „,. . „ . 



r, ^1 • • J.1 • 1 .cj. 1 • • „^„i- n Fig.TlB. — Echinocaris sublevis, 



Sjjathtocaris, there is a cleft beginning centrally After WMtneid. 

 at the highest point of the carapace. 



L. lutlieri Clarke, 1. c. 478, 1882. 



Aptychopsis Barrande, 1872. 



Differs from Peltocaris in the rostrum being triangular instead of 

 parabolical; and fvom. Discinocaris in having no suture indicating the 



separation of the two principal valves. 



A. primus Barr. 1. c. 457, PI. 33, 1872. Bohe- 

 mia. 



Genus Dicty^ocaris Salter (1860). 



Carapace ample, bent along the dor- 

 sal line, but not two-valved, largely 

 reticulate, the area of the reticulations 

 being convex. The shape of the car- 

 apace is rudely triangular, pointed or 

 rounded in front, truncate and pro- 

 :Fig.72.-Discinocarishrowniana. j,atnrau\ze, duccd behind, aud margined along the 



side view and disk, with the wedge-shaped ros- hinder and VCUtral cdgCS by a StrOUg 



trum in situ. After Woodward. r? 



furrow. 



D. sKmoni Salter, Ann. Mag. Nat. Hist. vol. 5, 1860, 162. 

 D. ramsayi Salter, 1. c. 162. 



Genus Dithyrocaris Scouler. 



Carapace large, apparently covering all but the last abdominal segment ; 

 "the rostrum minute or possibly (but not probably) absent" (Salter). 



