202 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



Measurements: Males, 2.9 to 7.5 mm; non-ovigerous females, 2.4 to 



7.6 mm; ovigerous females, 3.4 to 8.1 mm. The male holotype measures 



5.7 mm in length, 4.8 mm in breadth; a female paratype, 5.4 by 4.8 

 mm. 



Color: Ground color in life an ivory yellow, overcast with lavender 

 and blood red spots. Protogastric regions lighter. Chelipeds same as 

 carapace. Ambulatory legs banded with white on propodus. (Glassell, 

 1936) 



Carapace light aniline lilac with open irregular netting of dull cad- 

 mium orange, except on frontal regions where color is more red. Eyes 

 dull mauve. Chela color as in carapace, but netting pale and broken. 

 Fingers darker and slightly red. Ambulatory legs lighter than carapace 

 and netting bright and distinct. A white band at distal end of propodus. 

 Ventral side white. (Petersen, of a live specimen from Costa Rica) 



Ecology: Glassell (1936) reported the species to be commensal with 

 a large hermit crab, Petrochirus calif orniensis Bouvier; he noted that 

 usually a pair of the porcellanid occupies a shell, but that one or three 

 specimens may be present. Steinbeck and Ricketts (1941) found it "in 

 container of hermit crabs from Estero de la Luna (where Dardanus 

 sinistripes and Pagurus albus were taken)." At three Hancock Foun- 

 dation stations (209-34, 480-35, 681-37) large shells were recovered 

 which may have contained specimens of Porcellana cancrisocialis. The 

 specimen taken by Dawson and Durham at Guaymas was from "mud 

 flats," perhaps from shells. 



The large number of stations for which no commensalism was noted 

 indicates that crabs of this species are probably free-living most of the 

 time, only occasionally seeking shelter in shells with hermit crabs. The 

 species has been recovered free-living from shore to a depth of 54 

 fathoms. Analysis of 23 Hancock Foundation dredging stations for 

 which bottom data are available shows the following: sand (9 stations), 

 sand and shell (3), sand with kelp (2), sandy mud (2), mud (2), 

 mud and shell ( 1 ) , sand and nullipores ( 1 ) , sand, gravel, and mud ( 1 ) , 

 corallines (1), corallines and nullipores (1). Substrates of sand and 

 of mud were recorded for specimens from the Askoy Expedition and 

 from Hamburg Museum collections, respectively. Glassell (1937) re- 

 ported the species from sand with weed. 



Ovigerous females have been encountered in every month from De- 

 cember through May, and in August. 



Relationships: This species is very closely related to Porcellana 

 say ana (Leach), 1820, from the western Atlantic. The latter form dif- 



