l82 SMITHSONIAN MISCELLANEOUS COLLECTIONS 



its external hiatus, coming in contact with the eye. The movable 

 peduncle of the antennas is more or less crested. The epimeral 

 pieces of the carapax are posteriorly continuous and entire. Clieli- 

 peds broad and depressed. Dactyli of the ambulatory feet of the 

 normal form — that is, short and robust — without supplementary 

 unguicles. 



The name Pisidia of Leach can properly be retained neither for 

 Petrolisthes nor for Porcellana restricted, since Leach's genus was 

 founded upon a purely fanciful character, and about half its species 

 will go in one of those genera and half in the other. 



The species of Petrolisthes are very numerous, inhabiting the 

 tropical and temperate zones in both oceans. They are strictly lit- 

 toral in station. The following species, heretofore described, may 

 be classed here, P. violacca being considered the type : 



Porcellana violacea Guerin. Porcellana dentata M. Edw. 



valida Dana. t anient osa Dana. 



rupicola Stimpson. boscii Savigny. 



elongata M. Edw. galathina Bosc. 



japonica De Haan. hirsuta Gray. 



asiatica Gray. edwardsii De S. 



polita Gray. tnberculata Guer. 



armata Gibbes. tuberculifrons M. E. & L. 



maculata M. Edw. tuberculosa M. Ed. 



lamarckii M. Edw. acanthophora M. E. & L. 



speciosa Dana. coccinea Owen. 

 scabricula Dana. 



288. PETROLISTHES SPECIOSUS (Dana) Stimpson 



P1.ATE XXII, Fig. 2 



Porcellana speciosa Dana, U. S. Expl. Exped., Crust., i, 417, pi. xxvi, 



fig. 8. 

 Petrolisthes speciosus Stimpson, Proc. Acad. Nat. Sci. Phila., x, p. 241 



[79], 1858. 



This species in life is of a purplish or reddish-brown color above, 

 with a bluish-white hoariness in old specimens. Beneath deep crim- 

 son. It is sometimes found of a much larger size than is mentioned 

 by Dana; thus, in a specimen from Japan, the carapax measures 

 0.61 inch in length and 0.575 in breadth; the hand 1.05 in length. 

 Most specimens differ somewhat from Dana's figure, as follows : 

 The angles are less rounded and the carpus in the right cheliped has 

 fewer teeth on the anterior margin, is not so closely serrated on the 

 posterior margin, and is more prominent at the external angle. 



