Boone, Crustacea, Cruises of ''Eagle" and ''Ara," 1921-28 163 



Synonymy. — Neptunus vocans A. Milne Edwards, Bull. Philom. Soc, 

 series 7, tome II, p. 225, June, 1878.— Miers, Kept. ''Challenger" 

 Zool., Brachyura, vol. 17, p. 174, 1886. — ^A. Milne Edwards and 

 BouviER, Exped. Sei, du Travailleur et du Talisman, Crust. 

 Deeap., p. 68, pi. 14, figs. 6-9, 1900. 



Portunus (Portunus) xantusi (Stimpson). 



Plate 56, figs. A and B. 



Name: This species was named in honor of the collector, Mr. J. 

 Xantus. 



Diagnostic characters : This species is readily distinguished from 

 aU other West American Portunids by the presence of a prominent 

 rugose ridge, paralleled anteriorly by a deep sulcus, which curve out 

 toward the base of the strong lateral tooth. 



Type: Prof. Stimpson states that the species was "very common 

 on the beaches of Cape St. Lucas" (L. C). His type material was 

 originally in the collections of the IT. S. National Museum, but is no 

 longer extant. 



Material examined : One young male and one larger male from the 

 Perlas Islands, March, 1928 ; one adult male and a female from Punta 

 Arenas, Costa Rica, February, 1928, taken by the "Ara," William K. 

 Vanderbilt, commanding. 



Distribution : Pelagic from Santa Monica Bay, California to Chile. 



Technical description : Carapace oval, 21.5 mm. long, 35 mm. wide 

 from tip to tip of lateral spines ; interorbital space 8 mm. wide. There 

 are four frontal teeth in addition to the bifid preorbital teeth ; these 

 four are triangulate, equally prominent, separated by sinuses equal 

 in size to the teeth; in older specimens the outer pair are slightly 

 wider than the inner pair. There are nine anterolateral teeth, includ- 

 ing the postorbital, which is subacute and a trifle broader than the 

 seven lateral teeth, which are acute, the tips pointing forward, the 

 posterior lateral margin convex ; the ninth or postlateral tooth is about 

 twice as long as the preceding tooth and is directed straight outward. 

 The postlateral margins are concave and are about as long as the an- 

 terolateral margins; the posterior margin is about as wide as the 

 orbital space and is relatively straight. The dorsal surface of the 

 carapace is pubescent and granulose; there is a prominent rugose 



