232 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 24 



scarcely visible, except very faintly on the intestinal region. The small 

 scattered granules covering the protuberances were not clearly marked 

 except toward the outer and frontal margins. The median notch of the 

 front was less distinct than is shown in Glassell's illustration of the 

 holotype. Some of these differences may be due to the soft-shelled con- 

 dition of the type. 



Material examined: Punta Pefiasco, Sonora, Gulf of California, 

 shore; April 12, 1937; collected by S. A. Glassell; male, holotype (San 

 Diego Natural History Museum Cat. No. 1131). 



Puntarenas, Costa Rica, 6-8 fathoms; May 6, 1912; collected by R. 

 Paessler; one female (Hamburg Museum Cat. No. K26847). 



Measuremetits: The male holotype measures 3.5 mm in length, 3.1 

 mm in width. The only other specimen seen, a non-ovigerous female, 

 is 2.9 mm long. 



Color: In alcohol, cream tipped with orange-red. (Glassell) 



Ecology: Found among gorgonian corals, sponges and bryozoan 

 growths, at extreme low tide. (Glassell) The Costa Rica specimen was 

 taken in 6-8 fathoms, along with Pisidia magdalenensis (Glassell). The 

 substrate at the latter station was not recorded. 



Glassell (1938a) mentioned an ovigerous female, apparently taken 

 with the holotype in the month of April. The whereabouts of this speci- 

 men is unknown. 



Remarks: Because of its minute size, Ulloaia perpusillia is extremely 

 difficult to examine in detail. Probably for the same reason, it is very 

 rare in collections; the Costa Rica specimen listed above is only the 

 third to be noted. It could be an abundant and wide-ranging form 

 and still be overlooked by most collectors. 



Range: Known only from the two localities listed above, Punta 

 Pefiasco, Gulf of California, and Puntarenas, Costa Rica. Shore to 8 

 fathoms. 



POLYONYX Stimpson 1858 



Poly onyx Stimpson, 1858, p. 229 (type species Porcellana inacrocheles 

 Gibbes, 1854, by original designation). 



Carapace transversely ovate or subquadrate, usually markedly 

 broader than long; strongly convex, surface usually smooth, shining. 

 Front much deflexed, appearing nearly transverse in dorsal view. 

 Eyes small, retractile. 



