THE SPIDER CRABS OF AMERICA 137 



Measurements. — Male (20146), length 21.7, width 17.7 mm. 

 Female of large size (20146), length 15, width 12.2 mm, Male, var. 

 A (21879), length 11, width 8 mm. Male, var. B (21875), length 

 13.4, width 12.1 mm. 



Range. — Monterey Bay, California, 45 fathoms, 1 specimen (Wey- 

 mouth). From Venice, California, to Bay of Panama. Depth, 33^2 

 to 66 fathoms. 



Material examined. — See table, pages 134-135. 



Genus DASYGYIUS Rathbun 



MicrorhTjnchus Bell, Proc. Zool. Soc. London, vol. 3, 1835, p.* 88; type, 

 M. gibbosus Bell; Trans. Zool. Soc. London, vol. 2, 1836, p. 40. Name 

 preoccupied by Megerle von Miihlfeld for a genus of Coleoptera in Dahl's 

 "Coleoptera und Lepidoptera" [price list], Wien, 1823, p. 63.^^ 



Cyrnus Audouin in de Haan, Fauna Japon., 1839, p. 86 (as synonym of 

 subgenus Microrhynchus) . Name preoccupied by Stephens in 1836 for 

 a genus of insects. 



NeorhT/nchus A. Milne Edwards, Crust. R^g. Mex., 1879, p. 186 (substi- 

 tuted for Microrhynchus). Name preoccupied by Sclater in 1869 for a 

 genus of birds. 



Dasygyius Rathbun, Proc. Biol. Soc. Washington, vol. 11, 1897, p. 164 

 (substituted for Neorhynchus). 



Carapace ovate, terminating in a short rostrum. Postocular tooth 

 well developed. A fissure at middle of upper margin of orbit. Eyes 

 stout, constricted before the cornea. The basal segment of the 

 antennae bears a tooth or spine at its extremity, and its inner crest 

 projects downward. Merus of maxillipeds cordiform. Chelipeds 

 short, merus curved, subtriangular in section; fingers about as long 

 as palm. Ambulatory legs subcylindrical, hairy, the first and last 

 pairs shorter than the second and third; dactyli long and slender, 

 slightly curved. In the male the last two segments of the abdomen 

 are fused, in the female the last three segments; the first segment is 

 armed with a spine or tubercle and is much longer than the second. 



Only two species known, from the west coast of middle America. 



KEY TO THE SPECIES OF THE GENUS DASYGTIUS 



A'. Carapace convex. Rostrum bifid. Extremity of male abdomen narrowly 

 triangular gibbosus, p. 138 . 



A-. Carapace flattened. Rostrum simple. Extremity of male abdomen 

 broadly rounded depressus, p. 138. 



" The name of the genus is followed by a list of species included. 



