COMPLETE HAIG: EASTERN PACIFIC PORCELLANIDAE 21 



unaware of Philippi's obscure reference. Cano recognized the similarity 

 of his Porcellana pulchellula to P. mitra, distinguishing it only by the 

 distinctly trilobate form of the front, three instead of two carpal spines, 

 and the more granular surface of the carpus. 



The specimen from the Novara Expedition identified by Heller 

 (1865) as Porcellana mitra Dana had as its locality "Siidsee." This 

 suggests that it might have been collected in the Indo-Pacific region, 

 in which case it would represent an entirely different species. However, 

 many of Heller's locality records are known to be unreliable (cf. 

 Chilton and Bennett, 1929, p. 732), and the specimen could have been 

 collected at Valparaiso, where the Novara stayed for some time. Heller's 

 brief description certainly fits the present species. 



Range: Callao, Peru, south to Estrecho de Magallanes, Chile. Shore 

 to about 7 fathoms. 



PETROLISTHES Stimpson 1858 



Petroltsthes Stimpson, 1858, p. 227 (type species Porcellana violacea 

 Guerin, 1831, by original designation). 



Carapace rounded or subquadrate, usually about as broad as long. 

 Front triangular or trilobate, often rather prominent and produced be- 

 yond eyes. Eyestalks short and stout, retractile. 



Basal segment of antenna not produced forward to meet anterior 

 margin of carapace; either not produced inward, or with a distinct in- 

 ward projection forming a partial suborbital margin. 



Basal segment of antennule large, broad, in dorsal view sometimes 

 partially visible beyond front; anterior margin occasionally sinuate, 

 but more often armed with spines, lobes, or other projections. 



Chelipeds large, subequal in size; carpus variable, from about one 

 and a half to over three times as long as wide; manus broad and 

 flattened, its dorsal surface occasionally somewhat swollen. 



Walking legs of moderate length, somewhat flattened; propodus 

 with movable spinules on posterior margin ; dactylus ending in a simple 

 spine, with small movable accessory spinules on posterior margin. 



Telson of abdomen almost invariably composed of seven plates. 



The genus is worldwide in distribution, and contains numerous 

 species. 



