280 BULLETIN 152, UNITED STATES NATIONAL MUSEUM 



B^. Regions fairly well indicated, especially the hepatic and anterior gastric 

 regions. Frontal lobes each subdivided by a broad shallow sinus. 

 Dark color covering about two-thirds of dactylus of chelipeds. 



patagonicus, p. 284. 



ANALOGOUS SPEOES OF PLATYXANTHUS ON OPPOSITE SIDES OF THE CONTINENT 



Atlantic Pacific 



crenulatus cokeri 



PLATYXANTHUS ORBIGNYI (Milne Edwards and Lucas) 



Plate 115; Plate 116, Figure 2 

 Xaniho orbignyi Milne Edwards and Lucas, d'Orbigny's Voy. Amer. Mer., 



vol. 6, pt. 1, 1844, p. 14; atlas, vol. 9, 1857, pi. 7, fig. 1-le (type-locality, 



Chili; type in Paris Mus.). 

 Platyxanthus orbignyi A. Milne Edwards, Ann. Sci, Nat., ser. 4, vol. 20, 1863, 



p. 280. 



Z>m^nosis. —Antero-lateral margin cut into nine large teeth. Merus 

 of outer maxiliipeds longer than broad; two punctate lines on ischium. 

 Ambulator}'^ legs very broad. 



Description. — Carapace moderately convex, uneven; regions out- 

 lined by shallow furrows; a broad median furrow extends backward 

 from the front margin. Surface paved with crowded flattened gran- 

 ules; a raised line runs oblique!}^ backward from the last lateral tooth. 

 Antero-lateral borders broadly arcuate, occupying three-fifths of the 

 length of the carapace; they are cut into nine strong teeth trending 

 forward and a few secondary teeth, not counting the first or orbital 

 tooth; the last tooth is simple; the eight intermediate ones are resolv- 

 able by the depth of the emarginations into three groups of two, four 

 and two teeth respectively. The numerous marginal teeth therefore 

 correspond to the five teeth or lobes in other species of the genus and 

 in most species of Xanthidae. Postlateral margin slightly sinuous. 

 Front divided into four subequal triangular blunt teeth; median 

 smus deeper than the lateral. Inner upper tooth of orbit short but 

 well marked; the three fissures of orbit deeply cut; outer suborbital 

 tooth more advanced than the one above it; inner suborbital tooth 

 as advanced as or more advanced than the front. 



Ischium of outer maxiliipeds with a longitudinal row of linear 

 punctae near inner margin; another row of round and more distant 

 punctae at inner third; merus subtriangular, elongate, outer angle 

 opposite inner tooth. Chelipeds massive, ver}' unequal; a low pro- 

 tuberance on upper border of arm and an acute tooth at inner angle 

 of wrist; palms swollen; fingers shorter than middle length of palm, 

 gaping; the dark color of the dactylus does not cover the basal fourth, 

 that of the immovable finger is not continued on the palm; prehensile 

 teeth white. Under part of carapace, upper border of arm and mar- 

 gins of legs hairy. 



Color. — Red spotted with yellowish above, yellow below, fingers 

 and nails black (A. Milne Edwards and Lucas). 



