SUPER-ORDER V 



MALACOSTRACA 



667 



Emmelezoe, Jones and W. Valves of carapace elongat--, naimu, ami with distinct 

 ocular node; other cephalic nodes wanting. Surface- with tint- longitudinal raised 

 striae. Abdomen unknown. Silurian. 



Sub-Order D. RHINOCARINA. Clarke. 



Carapace iirith a free rostrum and narrow median dorsal plate separated from, the 

 valves by a straight or slightly curving hinge at each side. Ocular nodes clearly defined, 

 with a distinct optic pit at the summit. 



Family 1. Rhinocaridae. Clarke. 



Valves articulated by interlocking at the single point where they come in contact. 

 Abdominal segments two to three. Posterior margin of carapace concave and spined. 



Bhinocaris, Clarke (Fig. 1376). Carapace smooth, with tine raised longitudinal 

 striae; divergent, branching furrows radiating back- 

 ward from the eyes. Lateral carina very faint. 

 Abdomen with two or three free segments, the last 

 much longer than the others ; all diagonally striated 

 or chevroned. Caudal plate with a broad telson and 

 two long and 



A B 



slender cercopods 

 fimbriated on 

 their margins. 

 Middle Devonian; 

 New York. 



M e s o t h y r a, 

 Hall and Clarke 

 (Fig. 1377). 

 Carapace large, 

 valves distinctly 



interlocking at Eye? B, Hinge of ri-ht valve. 



point of contact. 



Lateral carinae strong, crenulated at the summit, Abdomen with two broad, exposed 

 segments. Telson shorter than the cercopods, the latter setigerous. Upper Devonian ; 

 New York. 



;l.:v -..ir.iLrfi:.^ 



FIG. 1377. 



Mi-rintliii-ii Vri'nn!, Hall. Portage Group 

 (Upper Devonian) ; Ithaca, New York. A, 



FIG. 1376. 



/'//(' rtocori* columbina, Clarke. Ham- 

 ilton Group; Canandaigua Lake, NI-W 

 York. A , E, Dorsal and lateral views of 

 animal. />', I), Same of rostrum, en- 

 larged. C, Median plate, enlarged. 



Dithyrocaris, Scouler (Argas, Scouler). Very similar in aspect to Mesothyra, 

 with the junction line of the valves overlapped by a (free ?) rugose ridge or narrow 

 interstitial plate. Rostrum not observed. Devonian and Carboniferous ; Scotland. 

 Rachura, Scudder, known only from the abdomen and telson, is probably allied t<> 

 Dithyrocaris. Carboniferous; Illinois. 



Chaenocaris, Jones and W. Carapace valves with a very strong lateral ridge and 

 without posterior spine. Carboniferous ; Scotland and Belgium. 



Sub-Order E. DISCINOCARINA. Clarke. 



Sub-circular or oval shields with a triangular rostrum filling an anterior notch 

 Surface ornamented with raised concentric lines. Substance chitinous. 



VOL. I - 2 U 



