162 



thirds ; propodus slightly longer than carpus ; fingers parallel, slightly 

 deflected from the line of the palm, without teeth, their inner and outer 

 surfaces densely pubescent. 



Manus of the second pair minutely spinulose to the base, of the fin- 

 gers ; carpus and meros spinulose, the spinules larger on the under 

 surface, where they form distinct longitudinal rows. 



Posterior legs smooth, cylindrical, sparsely pubescent. 



Terminal segment of abdomen with seven spinules, three at the tip 

 the central one fixed, the lateral ones articulated, and two pairs situ- 

 ated farther forward, the anterior pair at about the middle of the 

 length of the segment. 



Three or four specimens were taken in Mulege River, on the West 

 coast of the Gulf of California, by W. I. Fisher. 



This species closely resembles P. dasydactylus Streets (Proc. Phil. 

 Acad., 1871, 225) which is quoted by Kingsley, in his List of North 

 American Caridea" (Bull. Essex Inst., Vol. X, Nos. 4, 5, 6) as a syno- 

 nym of P. forceps M. Edward. The principal differences traceable are 

 in the proportions of the joints of the first pair of legs, the maims in 

 the present species being shorter than in P. dasydactylus, in the greater 

 length of the articulations of the second pair in this species, as com- 

 , pared with their thickness ; and in the spines of the terminal abdomi- 

 nal segment, which are only five in Dr. Streets' species. 



The differences are so small, and the resemblances so great, as to 

 suggest the .possibility of actual near relationship; and it is not im- 

 probable that in this form we meet with the descendants of such of 

 the Atlantic P. forceps as penetrated into the Pacific when the oceans 

 were connected at what is now the Isthmus of .Panama. 



The female resembles the male, except in the second pair of limbs, 

 which are much smaller, smooth, shorter, and more slender, and have 

 the proportions of the joints reversed, the manus shorter than the 

 carpus, and the latter shorter than the meros. 



The specimens were obtained in August, and the females were 

 loaded with ova. 



The teeth on the upper side of the rostrum vary somewhat, the tip, 

 which is blunt in one specimen, is bifid in another, and one of the 

 .males has only eight teeth on the upper edge. 



Following are the dimensions of a male and female : 



$ ? 



Total length, . . . . . . 105 millims. 82 millims. 



Length of carapax, including rostrum, . 51 " 37 " 



" " flagellum of antennae, . 110 " 95 " 



" " outer flagellum of antenuulae, . 90 " " 



" " first pair of legs, ... 39. " 25 " 



