SUBCLASS II 



EUCRUSTACEA— PHYLLOCAEIDA 



753 



Rhinocaris Clarke (Fig. 1458). Carapace smooth, with fine raised longitudinal 

 striae ; divergent, branching furrows radiating backward 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 



Fig. 1458. 



Rhinocaris columbina Clarke. Ham- 

 ilton Group ; Canandaigua Lake, New 

 York. .-1, E, Dorsal and lateral views of 

 animal. B, D, Same of rostrum, en- 

 larged. C, Median plate, enlarged. 



Fig. 1459 bis. 



Mesothyra oceatii Hall. Portage Group 

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

 Eye. B, Hinge of right valve, i/j. 



Fig. 1459. 



Mesothyra oceani HaU. Upper Devonian; New 

 York. Reconstruction of carapace and abdomen. 

 1/2 (after Hall and Clarke). 



telson and two long and slender cercopods fimbriated on their margins. Middle 

 Devonian ; New York. 



Mesothyra Hall and Clarke (Fig. 1459). Carapace large, valves distinctly inter- 

 locking at 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. 



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 to 

 Dithyrocaris. Carboniferous ; Illinois. 



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

 without posterior spine. Carboniferous ; Scotland and Belgium. 



VOL. I 



3 c 



