PART 1 GARTH : PACIFIC OXYRHYNCHA 397 



and 8.0 mm, respectively. Ovigerous female, length 12.8 mm, width 



12.2 mm. 



Color in life: Carapace light pomegranate on frontal area; other 

 areas rose. Eye light grape green. Chelipeds olive buff densely overcast 

 with tiny rose colored dots extending to middle of fingers. Ambulatory 

 legs similar to chelipeds. Ventral side pale olive buff with a few scattered 

 spots of rose color. (Petersen, of a specimen from Isabel Island, Mexico) 



Habitat: Broken shell, broken coral. (Rathbun) Rock, frequently 

 with red algae attached ; rock and sand ; coral, nullipore, and rock. 

 (Garth) When dredged, Velero III specimens were obtained 6 times 

 on sandy bottom, 3 times on muddy bottom, and 13 times on nullipore 

 or coralline bottom. Shell was present in a third of the sand and mud 

 bottom stations. 



Depth : Intertidal to 44 fathoms. 



Size and sex: Males are from 4.7 to 13.0 mm, females from 4.5 to 



13.3 mm, ovigerous females from 7.8 to 12.8 mm, young from 4.5 mm. 

 Breeding: Ovigerous females were encountered by Hancock collec- 

 tors in the Gulf of California in February, March, and May, and by 

 C. L. Hubbs at Acapulco, Mexico, in September. 



Remarks: The occurrence of Microphrys triangulatus, rather than 

 M. branchialis, at Isabel and Tres Marias Islands shows the value of 

 critical determinations in underscoring faunal affinities. Here the rela- 

 tionships are definitely with the Gulf of California, rather than with the 

 open Pacific coastline, for whereas M. branchialis is represented abun- 

 dantly on the open coast from Dewey Channel, Lower California, to La 

 Libertad, Ecuador, and but exceptionally in the Gulf of California, M. 

 triangulatus is overwhelmingly present in the Gulf and but sparingly 

 represented elsewhere. 



The identification of the Acapulco specimens, two females, was made 

 principally on the strength of the conical lateral spine, and of the Pana- 

 manian specimens, a pair, by the greatly enlarged cheliped and broadened 

 palm of the male. The conical spine should not be used without supple- 

 mentary specific characters in more southerly latitudes, as with Cocos 

 Island specimens, because Galapagos Islands specimens of Microphrys 

 triangulatus exhibit a sharp spine like that of M. branchialis (see Rath- 

 bun, 1925, p. 506). The shortening and widening of the carapace, as 

 compared to M. branchialis, and the "shoving up" and "smoothing off" 

 of the branchial prominences, as noted by Rathbun, combine to give the 

 species its triangulate appearance. When seen in life, brightly colored 

 and covered with bryozoan or other encrustation, its resemblance to a 

 coralline alga is striking. 



