NO. 3 GARTH : SOME NEW SPECIES OF BRACHYURAN CRABS 55 



merus which fades out toward the base of the ischium. Anterior ex- 

 tension of septum of branchial channel trilobate. 



Merus of cheliped with conspicuous pearly granules. Carpus and 

 manus smooth and bare to the naked eye, microscopically granulate. 

 Male cheliped one and one-half times the length of carapace. Chelipeds 

 subequal in both sexes. 



Sternum and abdomen of female smooth and polished, of male micro- 

 scopically flat granulate. 



Ambulatory legs smooth and bare. Lower margin of merus of fourth 

 walking leg entire. 



Color in alcohol: This beautiful crab has the same irregular splotch- 

 ing of dark red-orange on cream buff that characterizes R. ornata ( Ran- 

 dall) (1839). 



Color in life: Ground color of carapace olive buff almost covered 

 anteriorly with dots of chrome yellow. Large, regular designs vinaceous 

 russet, smaller patches paler and more orange. Posterior spines white. 

 Cheliped yellow to pale buff, merus covered with carrot red, carpus and 

 manus with a coarse netting of the same color. Merus of ambulatory 

 legs pale yellowish white at base blending into intense scarlet on distal 

 portion. Remaining segments yellowish white; dactyl yellow tipped. 

 (Petersen) 



Distribution: The 30 specimens collected at 5 stations of Velero 

 III in the Gulf of California in 1936 and 1937 range from Angel de 

 la Guardia Island to Willard's Point, and it is presumed that the species 

 ranges northward to the mouth of the Colorado River. 



Remarks: The effectiveness of the thermal barrier to the distribu- 

 tion of species is perhaps not better illustrated than in the case of this 

 crab, which is the Gulf counterpart of the well-known R. ornata of the 

 open Pacific. Essentially a cold-water species, R. ornata is not known to 

 occur south of Magdalena Bay, while R. angelica was not encountered 

 by Allan Hancock Expeditions south of Puerto Refugio, Angel de la 

 Guardia Island, where 13° C. surface temperatures were recorded. 

 Apparently the species do not communicate around Cape San Lucas, 

 where the surface temperature was found to be 20° C. Unfortunately, 

 relative temperatures at depths at which specimens were dredged were 

 not taken. 



The points which separate R. angelica from R. ornata are as fol- 

 lows: (In these comparisons a specimen of ornata of like size and sex 

 with the holotype of angelica was used.) 



