OXYSTOMATOUS AND ALLIED CRABS OF AMERICA 21 



the carina extending backward for a short distance on the carapace. 

 Superior margin of orbit armed with three acute teeth, the second of 

 wliich is curved forward; the anterior tooth is separated from the 

 rostrum by a deep rounded sinus, from the second tooth by an angular 

 notch ; the second tooth is separated from the third by a nearly straight 

 interval; the third tooth hes some distance in front of the posterior 

 end of the orbit. Back of the orbit there is a long and strong pro- 

 curved spine on the margin of the carapace. Eyestalks compressed, 

 equal in length to one half the width of the carapace. Second segment 

 of the third maxilliped equal to the third joint, and crossed by a 

 piiiferous line; third segment notched at the antero-internal angle. 

 Cheliped: Merus microscopically spinose above, setose below, and 

 with an inner distal spine, tip sometimes broken off; carpus minutely 

 rugoso-spinulose, the superior distal angle projecting as a sharp tooth; 

 propodus lightly rugose, upper and lower borders margined, unarmed, 

 palmar edge irregularly and inconspicuously toothed; dactylus 

 without any prominent tooth. The dactylus of the third pair of legs 

 has a very convex internal border, the dactylus of the fourth is long, 

 narrow, and spatulate. Abdomen setose; telson obtuse at the end. 

 (Faxon.) 



Measurements. — Type specimen, length of carapace 12, breadth 

 8.6 mm. 



Range. — ^From Cape St. Lucas to Ecuador; 7 to 70 fathoms. 



Material examined. — See table 4, p. 22. 



Genus LYREIDUS De Haan 



Lyreidus De Haan, Fauna Japonica, Crustacea, p. 138, 1841 (type, L. tridentatus 

 De Haan).— Alcock, Journ. Asiat. Soc. Bengal, vol. 65, p. 294 [299], 1896. 



Carapace elongate-obovate, the anterolateral margins independent 

 and gradually convergent; strongly convex from side to side and 

 slightly convex from before backward; smooth and polished, regions 

 undefined. Fronto-orbital border less than half the breadth of 

 carapace. Eyes small; eyestalks short, broad at base, orbits hardly 

 oblique. Antennules about equal m size to antennae; antennae with 

 a stoutish peduncle and rather short slender flagellum, the peduncle 

 not concealing the antennulary peduncle. Merus of external maxil- 

 lipeds a little longer than ischium. Sternum broad as far as the 

 bases of the first pair of true legs, then becoming narrow. Last 

 pair of legs abnormally short and slender arising well in advance of 

 the posterior pair. The abdomen in both sexes consists of seven 

 distinct segments. (Alcock.) 



West Atlantic, Indian, and west Pacific Oceans. 



