ACADEMY OF SCIENCES. 107 



The upper part of the carapax is thickly tomentose, except upon the ridges. 

 This species is well marked, and readily distinguished from the following. 

 No. 23. Female, dried. Mazatlan. Hy. Edwards. 



Amphitrite paucispinis. Lockington. 



Inter-antennal front four-lobed; pre-orbital spines slightly two-lobed. 

 Antero-lateral spines were nearly equal in size, except the ninth, •which is 

 twice the length of the others. The outline of front portion of carapax be- 

 tween the last antero-lateral spines, on each side, is a regular ellipse. Pos- 

 terior to the last antero-lateral spine the carapax contracts suddenly in width, 

 so that the postero-lateral margins are L-shaped. Meros of first pair with 

 four spines on its anterior margin, the proximal smallest. Carpus with one 

 spine on the interior upper margin, and two on the exterior. Manus with 

 one spine only, on its upper margin, forming the extremity of a carina. Four 

 slightly beaded ridges on the outer side of the manus. Fingers sulcate, 

 tubercular on the palmar margin, the movable finger with a large tubercle at 

 the base. Second, third, and fourth pairs of limbs slender; penultimate 

 joint of fifth pair sulcate and surrounded, as is also the last joint, with a reg- 

 ular fringe of hairs. Areolation of carapax very distinct; the summits of each 

 region granulated. 



The dimensions of two of the largest specimens, both female, are as fol- 

 lows: 



M. M. M. M. 



Extreme width from tip to tip of spines 40 54 



Greatest length 23 30 



Localities — Angeles Bay, Mulege Bay, both in the Gulf of California; 

 Magdalena Bay, West Coast Lower California. 



The specimens were collected at low tide in August and September, and 

 many of the females have the ova attached. 



No. 24. Two males, dried. Magdalena Bay, West Coast Lower Califor- 

 nia. Fisher and Lockington. 



Arceneus bidens. S. I. Smith. Report Peabody Acad. Sci , 1869, p. 90. 



Callinectes sp? "Agrees with Ordway's C. arcualus. Bost. Jour. Nat. Hist. 

 VII, p. 578, except that there is only one distinct spine on the 

 carpus of the chelipeds." S. I. Smith, loc. cit. 



In my last paper upon this subject, two species of Maioid crabs mentioned 

 in a "Catalogue of Crustacea from the Isthmus of Panama," by T. Hale 

 Streets, was included, viz.: Homalacantha hirsuta (T. Hale Streets), and 

 Mithraculus coronatus (Stimpson). Mr. Streets does not state on which side 

 of the Isthmus the various species enumerated in his catalogue were col- 

 lected; therefore, although I am aware that in some cases the same species 

 occurs on both sides, I shall not in future include in this catalogue any but 

 undoubtedly Pacific species. 



