MUSEUM OF COMPARATIVE ZOOLOGY. 151 



from the cavity of the orbit by a broad process of the basal segment. Merits 

 of outer niaxillipeds notched at the antero-internal angle. Legs of moderate 

 length; carpus of chelipeds elongated, not carinated; chela elongated and 

 slender, fingers canaliculate within, but liot spoon-shaped at their tips, their 

 prehensile edges meeting throughout most of their length, not distinctly 

 toothed ; ambulatory legs spinose. Abdomen (male) seven-jointed, terminal 

 joint short and broad. 



This genus is proposed for the reception of an interesting Maioid dredged 

 in 182 fathoms on the west coast of the Isthmus of Panama. It combines 

 in one form characters of the genera Maia, Gydomaia, Paramithrax (subg. 

 Leptomithrax), and Schizophrys. In its general aspect it bears a close resem- 

 blance to j¥aia, and the likeness is enhanced by the small eyes and slender 

 eyestalks, the elongated wrist and hand, and the short epistome. It differs 

 from Maia in having a much broader carapace, a less deeply cloven rostrum, 

 spinose legs, supra-ocular spines, and trenchantly in the exclusion of the an- 

 tennal flagellum from the orbit by a process of the basal segment of the antenna. 

 In the latter regard it agrees with the genus C'yclomaia, the basal segment of the 

 antenna being very broad, three-spined on its distal border, and giving off a 

 process which separates the flagellum from the orbit by a wide interval ; it also 

 agrees with Cydomaia in having a short epistome, a short and broad terminal 

 abdominal segment, and supra-ocular spines. It differs from Cydomaia by 

 having a subtriangular carapace, longer rostral spines, and a less abruptly 

 declivous front. It is like Paramithrax and Sdiizophrys in the exclusion of 

 the basal antennal segment from the orbit, but this segment is much broader 

 than in these genera, and three-spined ; moreover, Maiopsis differs from Para- 

 mithrax and Sdiizophrys in having a more broadly triangular carapace, supra- 

 ocular spines, slenderer wrist and hand, less deeply cleft rostrum, and spinose 

 ambulatory legs. Like Sdiizophrys, it has an accessory spine on each rostr.il 

 horn. In the shape of the carapace Maiopsis is intermediate between Maia, 

 and Cydomaia. In the form of the fingers it stands between Maia and Para- 

 mithrax on the one side, and Schizophrys and Cydomaia on the other, as the 

 fingers, though canaliculate within, are but slightly excavated at the tips. 

 The synthetic character of the species upon which this genus is based suggests 

 the propriety of ultimately extending the scope of the old genus Paramithrax 

 so that it may embrace this form, together with Cydomaia and Sdiizophrys. 



Maiopsis panamensis, sp. nov. 



Dorsal surface of carapace thickly set with spines of various sizes and scat- 

 tered hooked setae. The largest spines are distributed as follows ; five on the 

 gastric region, one on the genital, one on the cardiac, four on the intestinal, 

 and about seven on each branchial region. Margin of carapace armed with 

 twelve prominent spines, three of which are on the hepatic region. The ster- 

 num is ornamented with small tubercles along each side of the abdomen. The 



