No. 10 garth: brachyuran fauna of the galapagos 471 



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



1934, 2 males, 1 young. 

 789-38. South Seymour Island, shore, Jan. 19, 1938, 1 large male 

 (photographed). 

 Measurements. — Largest specimen, male: length 40 mm, width 59 

 mm, cheliped (rigid) coxa to elbow 41 mm, elbow to tip of dactyl 57 mm, 

 chela 52 mm, height 29 mm, dactyl 27.5 mm. 

 Habitat. — Under rocks at low tide. 

 Depth. — Shore. 



Remarks. — A specimen from Hood Island was compared with the 

 type (USNM No. 2050) collected by Sternbergh. Stridulating ridges on 

 the inner side of the palm are a remarkable characteristic of the genus. 

 They play upon certain of the anterolateral teeth and appear capable of 

 producing sound. (See illustration.) 



Genus PILUMNUS Leach, 1815 

 Key to the Galapagos Species of the Genus Pilumnus 



A^ Lateral margin with 5 spines, including orbital; size large 



P. xantusii 



A^ Lateral margin with 5 teeth, including orbital ; size minute 



P. pygmaeus 



Pilumnus xantusii Stimpson 

 Plate 59, Figs. 1-5 ; Plate 79, Fig, 4 



Pilumnus xantusii Stimpson, Ann. Lye. Nat. Hist. New York, vol. 7, 

 p. 213 (85), 1860. Rathbun, Bull. 152, U.S. Nat. Mus., p. 486, 

 pi. 201, figs. 1-3, 1930. 

 Eriphides hispida Boone, Zoologica, vol. 8, no. 4, p. 237, fig. 87B, 1927; 



(not fig. 87A, which is E. hispida). 

 Pilu7nnus crosslandi Finnegan, Journ. Linn. Soc. London, vol. 37, p. 643, 

 1931. 

 Type locality. — Cape San Lucas, Lower California. 

 Types.— Cotypts in Paris Mus. and MCZ, No. 1259. 

 Range. — Cape San Lucas, Lower California (Xantus) ; Galapagos 

 Islands (as P. crosslandi Finnegan), (Crossland). 

 Atlantic analogue. — P. sayi Rathbun. 



Diagnosis. — Five anterolateral spines including exorbital. Outer sur- 

 face of major manus completely roughened. Meri of ambuatory legs 

 entire. Carapace narrow ; proportion of length to width 5 : 6. Carapace 

 and chelipeds covered with long hairs. 



