418 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



is very prominent, is bent at an obtuse and rounded angle and is 

 armed for nearly its whole length with a row of large tubercles. Near 

 the proximal lower corner of the inner surface there is a longitudi- 

 nally oblique stridulating ridge extending from the articulation 

 with the carpus to the lower marginal line of the palm almost below 

 the angle of the transverse ridge. The stridulating ridge is made up 

 of closely placed parallel lines oblique to the axis of the ridge and 

 subparallel to the lower margin of the palm. When the cheliped is 

 flexed the ridge plays against the line of granules on the lower or 

 anterior surface of the first ambulatory leg ; this line extends nearly 

 the whole length of the carpal segment and part way along the merus. 

 The third to sixth abdominal segments of the male are more com- 

 pletely fused than in stenodactylus. 



Color. Prevailing tint of carapace and limbs (in spirit) blue, of 

 varying intensity, shading in parts into greenish and on the fingers 

 of the chelipeds into white (Lockington). 



a 



FlG. 171. UCA MUSICA, MALE HOLOTYPE, X 3&. a, LOWEB VIEW OF LARGER, LEFT CHELA, 



SHOWING STRIDULATING RIDGE ', 6, ANTERIOR (LOWER) VIEW OF PORTION OF FIRST LEFT 

 LEG, SHOWING GRANULES WHICH PLAT AGAINST STRIDULATING RIDGE. 



Measurements. Male holotype, length of carapace 8, width of 

 same 12.9 mm. 



Range. From San Diego, California, to Mazatlan, Mexico; occa- 

 sionally farther north. 



Material examined. 



Vancouver Island, British Columbia; photographs of a male, 

 received from C. F. Newcombe (U.S.N.M.). 



Seattle, Washington; D'Arcy W.Thompson, collector; photographs 

 of a large chela (U.S.N.M.). 



Pichilinque Bay, Gulf of California, Lower California; Apr. 29, 

 1888; Albatross; 1 male holotype (22081). 



La Paz, Gulf of California, Lower California ; Dr. Thos. H. Streets, 

 U. S. Navy; 6 males (2294). 



Guaymas Bay, Gulf of California, Mexico; shore; Feb. 20, 1904; 

 Wm. Palmer; 1 male (31512). 



