228 BULLETIN 129^ UNITED STATES NATIONAL MUSEUM 



Genus OPLOPISA A. Milne Edwards 



Oplopisa A. Milne Edwards, Crust. R^g. Mex., 1879, p. 201; type, 0. spi7iipes 

 A. Milne Edwards. 



Near Pisa Leach, -^^ but differs in the form of the maxillipeds and 

 of the buccal cavity; the merus of the outer maxillipeds is much 

 dilated at its antero-external angle while truncate on the inner side; 

 the buccal cavity, instead of a straight anterior margin, is much 

 more advanced on the sides than in the middle portion. Carapace 

 pyriform, with two rostral horns and inner orbital angles spiniform. 

 Orbit incompletely closed below, the low border being separated from 

 the basal article of the antenna by a deep, wide cut; this article is 

 narrow, the movable part of the antenna is exposed in dorsal view. 

 Antennular fossettes large. (After A. Milne Edwards.) 



Known only from the type species. 



OPLOPISA SPINIPES A. Milne Edwards 



Plate 232, figs. 1 and 2 



Oplopisa spinipes A. Milne Edwards, Crust. Reg. Mex., 1879, p. 201, p. 

 15 A, figs. 5-5b (type-locality, in explanation of plate. Strait of Florida, 

 101 fathoms; type in Paris Mus.). — A. Milne Edwards and Bouvier, 

 Mem. Mus. Comp. ZooL, vol. 47, 1923, p. 11, fig. 8. 



Diagnosis.— Orbital margin unarmed except for the preorbital and 

 the postorbital spine. Carapace rough with spines and granules. 

 Antennae, buccal area, chelipeds and legs similar to Mithrax. 



Description. — Carapace thick, swollen, slightly hairy, regions 

 little marked. Four tubercles surmount the gastric region; three 

 of them are situated in advance in a transverse row, the fourth is 

 behind. wSome tubercles on the cardiac, branchial and hepatic 

 regions; between the tubercles the surface is covered with fine granu- 

 lations. Rostrum narrow, formed of two straight, divergent horns; 

 it is about one-third as long as the rest of the carapace. Postorbital 

 angle wide, triangular and pointed. Basal article of outer antennae 

 armed on its lateral margin with two spines, the anterior of which is 

 the most developed. Chelipeds of female very feeble, furnished on 

 the merus and carpus with short, obtuse spines. Ambulatory legs 

 not very long, covered with regularly disposed spines. (After A. 

 Milne Edwards.) 



Measurements. — Length of carapace including rostrum 12.5, 

 excluding rostrum 9, width of carapace 7 mm. (A. M. E.). 



Locality. — Known only from the type-locality, Strait of Florida, 

 101 fathoms. 



RemarTcs. — The figures of this species suggest strongly the young 

 of a Mithrax, but the want of spines on the upper and lower margins 

 of the orbit forbids its inclusion in that genus. 



'3 Edin. Encyc, vol. 7, 1814, p. 431. 



