No. 10 garth: brachyuran fauna of the galapagos 499 



Habitat. — Commensal in the periproct of the sea urchin, S. gibbosus. 



Remarks. — Schmitt (1939) is in error in stating that the first time 

 this species had been observed in the Galapagos Islands was on the Presi- 

 dential Cruise of 1938. Actually, it was taken on the Hopkins-Stanford 

 Expedition in 1898-99, but because of its commensal habit was observed, 

 not by the person who reported on the Brachyura, but by the person who 

 wrote up the echinoderms. H. L. Clark (1902) writes concerning 

 Strongylocentrotus gibbosus (Valenciennes) : 



"There are 11 dry specimens of this interesting urchin, from Tagus 

 Cove. They range in diameter from 16 to 40 mm. The color is a distinct 

 reddish-brown, the spines very dark olive, tipped with purplish; speci- 

 mens from Chile and Peru, whence this species was previously known, are 

 said to be gray. All but the smallest of the shells before me are distorted 

 by the presence of the parasitic crab so generally found in this urchin, and 

 in all but 3 the crab is present." (Italics are author's) 



Because the relationship between Pinnaxodes chilensis and this host 

 is a specific one, there can be no doubt that this was the species observed 

 by Dr. Clark. 



Family CYMOPOLIIDAE 



Genus GYMOPOLIA Roux, 1828 

 Key to the Galapagos Species of the Genus Cympolia 



Ai Second ambulatory leg not more than twice as long as carapace 

 B^ Two acuminate anterolateral spines, excluding exorbital 

 C^ Four slender frontal teeth. Carapace 1^ times broader 



than long C. lucasii 



C2 Two large, triangular frontal teeth. Carapace 1^ times 



as broad as long C. cortezi 



B2 Four truncate anterolateral spines, excluding exorbital. A 



sternal plate at base of third walking leg . . C. velerae 

 A2 Second ambulatory leg more than twice as long as carapace 



C. fragilis 



Gymopolia cortezi Crane 

 Plate 85, Fig. 2 



Cymopolia cortezi Crane, Zoologica, vol. 22, no. 3, p. 75, pi. 8, fig. 25, 

 1937. 

 Type locality. — Santa Inez Bay, Gulf of California; 60 fms. 

 Type.— N.Y. Zool. Soc. No. 36,895. 

 Range. — Known only from the type locality. 



