400 Mr. W. N. Lockington on the Porcellanidea 



The anterior border of the front is crenuLate when viewed 

 from above, and the antepenultimate joint of the antennal 

 base has an anterior spinous lobe. 



Stimpson mentions that most of his specimens had the 

 outer edge of the hand smooth. 



In one of the specimens there are two spines at the poste- 

 rior distal extremity of the meros of third and fourth pairs ; 

 the carpus of the right cheliped has four spines in front, that 

 of the left three ; and of the denticulations on the posterior 

 edge of the carpus only those at the distal extremity are 

 developed into spines, four on the left and three on the right 

 carpus. 



Thus this species is subject to considerable variation. 



My examples were from Mulege Bay, Gulf of California. 



Petrolisthes Edivardsius, De Saussure. 



As I have not seen De Saussure's description of this species 

 (Rev. etMag. de Zool. v. p. 366, pi. xi. fig. 3, teste Stimpson), 

 and have only Stimpson's short description (Crust. & Echi. 

 P. S. N. A. p. 40) to guide me, a description which will apply 

 equally well to P. arniata, I cannot be sure whether the two 

 specimens I have before me (and I have seen others like 

 them) are to be referred to P. Edivardsius or to a previously 

 midescribed specific type. If the latter should prove to be the 

 case, I would name the species P. liirtisjnnosus. 



To facilitate identification I subjoin a description. 



Entire surface of the carapax covered with short pubescence, 

 beneath which the surface appears to be somewhat striated. 



Gastric region elevated above the frontal and orbital, its 

 raised anterior boundary passing into the lateral margin of the 

 carapax above the level of the lateral spines. 



Front triangular, depressed, projecting as much as that of 

 P. riqncola ; preorbital spine acute, separated from the cen- 

 tral portion by a deep sinus ; postorbital spine acute, with a 

 broad base, above and behind which is a second, slender spine, 

 merging into the rounded antero-lateral border. 



A tooth on the penultimate, and a lobular tooth, ending in 

 a spine, on the antepenultimate joint of the antennal base. 



Distal border of the mandible with five or six small teeth. 



Meros of chelipeds with a spine in front ; carpus nearly three 

 times as long as wide, with four or five large triangular teeth 

 in front, ending in spines, followed by some spinose tubercles 

 at distal end ; central line of carpus elevated, posterior border 

 with about nine small teeth ; manus long and slender, an 

 elevated line running longitudinally along it at about one 

 third of its width from the raised interior margni ; outer 



