No. 10 GARTH : BRACHYURAN FAUNA OF THE GALAPAGOS 513 



Percnon gibbesi Rathbun, Bull. 97, U.S. Nat. Mus., p. 337, pi. 105, 1918. 

 Hult, Arkiv. for Zoologi, Band 30A, no. 5, p. 14, 1938. Schmitt, 

 Smithsonian Misc. Col., vol. 98, no. 6, p. 25, 1939. 

 Type locality. — Antilles. 

 Type. — In Paris Mus. 



Range. — From Cape San Lucas, Lower California, to Chile ; Galapa- 

 gos Islands (Hult) ; occurs also in the Atlantic. 



Diagnosis. — Carapace exceedingly flat and depressed, disclike. Legs 

 long and slender; anterior margins of meri armed with strong spines. 

 Chelae of adult male bulbous but compressed. 



Material examined (28 specimens from 9 stations). — 

 33-33. Black Beach, Charles Island, shore, Jan. 27, 1933, 1 female. 

 38-33. SE of Cormorant Point, Charles Island, shore, Jan. 29, 1933, 



3 males, 5 females (1 ovig.). 

 98-33. Darwin Bay, Tower Island, shore, Feb. 25, 1933, 1 ovig. 



female. 

 101-33. Darwin Bay, Tower Island, shore, Feb. 26, 1933, 1 male. 

 154-34. Reef north of Tagus Hill, Albemarle Island, reef, Jan. 15, 



1934, 2 females. 

 313-35. Black Beach, Charles Island, shore, Dec. 6, 1934, 1 female. 

 359-35. Osborn Island in Gardner Bay, Hood Island, shore, Dec. 19, 



1934, 2 males, 3 females. 

 784-38. Darwin Bay, Tower Island, shore, Jan. 17, 1938, 4 males, 2 



females (1 photographed). 

 789-38. South Seymour Island, shore, Jan. 19, 1938, 2 males, 1 young, 

 fragment. 

 Measurements. — Largest specimen, female: length 32.5 mm, width 

 34.3 mm ; largest male : length 30.0 mm, width 27.7 mm, cheliped 32.0 

 mm, chela 14.0 mm, height of palm 9.0 mm, dactyl 7.4 mm. These speci- 

 mens are of exceptional size. 



Color in life. — Carapace and merus of ambulatory legs brown above. 

 A fine white line bisecting carapace into right and left halves. Carpus, 

 propodus, and dactylus show increasing amounts of chrome orange, tRe 

 brown superior band narrowing with each article. Eyestalks and chelae 

 orange, though paler than legs. (Garth) 



Habitat. — Under large, turnable rocks in shallow, turbulent water. 

 Depth. — Shoal water. 



Remarks. — The Spray Crab is found in white water of knee to hip 

 depth. Its extreme flatness and propensity for keeping always on the under 

 side no matter how rapidly the rock is turned make P. gibbesi the most 

 difKcult to capture of all the Galapagos Grapsidae. Undoubtedly, many 

 more specimens are present than are seen. 



