Boone, Crustacea, Cruises of "Eagle" and "Ara," 1921-28 35 



Distribution: This species, which has hitherto been known only 

 from several stations in the Gulf of California, has its southern range 

 extended to Punta Arenas, Costa Rica, by the " Ara" material. 



Material examined : One specimen from Punta Arenas, Costa Rica, 

 March, 1928, by the "Ara." One, Canos Island, Costa Rica, Febru- 

 ary, 1928. 



Color: Ivory, 



Technical description : Anterior region of carapace with the me- 

 dian projection triangulate, separated from the lateral projections 

 by a concave margin ; the lateral projections are also triangulate, quite 

 as robust or slightly more so, and produced as far forward as the 

 median projection ; the apex of the lateral projection is a short, sharp 

 spine which arises from the margin ; the outer part of the frontal 

 margin is gently rounded and continues backward into the lateral 

 margin. The carapace is rather broadly ovoid, the anterior region 

 covered by a broad, soft, calcareous shield which is wider anteriorly 

 and rounded posteriorly ; there are three submedian tufts of long setae 

 on this shield; the posterior median dorsal plate of the carapace is 

 narrow, depressed, membranous, scarcely defined from the similar, 

 globose posterior lateral regions ; there are longitudinal series of tufts 

 of long setae on the median and posterior regions of the carapace also. 



The posterior region of the body is asymmetrical, soft, coiled; the 

 penultimate segment is semicalcareous ; the telson is transversely seg- 

 mented, the proximal part being approximately half as long as the 

 distal part, slightly asymmetrical and bilobed by a median longitud- 

 inal sulcus; the distal portion of the telson has a pair of incisions 

 midway the lateral margins, at which point the distal half of this 

 article is abruptly bent under ; the posterior margin is slightly asym- 

 metrical, with a small median incision, and is armed along its entire 

 margin with a series of irregular jagged teeth. The peduncle of the 

 uropoda is very substantial, being quite as long or longer than the 

 larger branch ; the latter has its outer distal face covered with a series 

 of scales which form an elliptical patch, which is. fringed around with 

 long setae; the smaller branch of the uropod is closely appressed to 

 the side of the peduncle and projects only a trifle beyond it distally ; 

 the outer distal face of the smaller branch also bears an elliptical 

 patch of scales. 



The chelipeds are large, markedly unequal, the smaller one scarcely 

 reaching the base of the propodus of the large chela. The large cheli- 

 ped is long and rather slender ; the merus has a few spinose granules 



