THE CANCROID CRABS OF AMERICA 



63 



Achelous spiniiuanaKiiiGShEY, Proc. Acad. Nat. Sci. Philadelphia, 1878, p. 320 [5]. 



Achelous spinimanus sviithii Verrill,'^ Trans. Connecticut Acad. Sci., vol. 13, 

 1908, p. 387, text-figs. 32 and 33, pi. 19, figs. 2, 2a; pi. 21, fig. 2 (type-locality, 

 off Hatteras, Albatross station 2285; type not yet returned to United 

 States National Museum. 



Diagnosis. — Lateral teeth 1 to 8 subequal; lateral spine not much 

 longer than teeth in adult; two spines on manus; superior outer sur- 

 face of manus with a longitudinal, tuberculate ridge; posterior distal 

 angle of merus of swimming legs armed with a spine. 



Description of large specimen. — Surface covered with a short close 

 pubescence except on the elevated portions; and on the anterior sur- 

 face of the merus of the ambulatory legs and on the sternum where 

 the pubescence forms a regular pattern with the bare spaces. Cara- 

 pace about 1% times as broad as long. Be- 

 sides the customary ridges on gastric, car- 

 diac and branchial regions, there is a curved 

 ridge beginning behind the orbit and con- 

 tinued along the base of the third to sixth 

 lateral teeth. The teeth of the front and 

 of the bidentate inner orbital angle form a 

 regular arch. Frontal teeth spiniform, the 

 sinuses U-shaped, the median sinus just 

 equal to or a little narrower than the lat- 

 eral; the lateral sinus is about the same 

 width as but shallower than the sinus on 

 the inner side of the inner orbital tooth; 

 the inner branch of this tooth is spiniform, 

 the outer branch an acute tooth. The 

 upper margin of the orbit has a prominent 

 denticle on the inner side of the outer fis- 

 sure. Outer orbital tooth equilateral, suborbital fissure V-shaped, 

 a marginal lobule on either side of it; inner infraorbital tooth more 

 advanced than the front. The second to eighth antero-lateral teeth 

 shallow, sharp-pointed, ninth or lateral spine half again as long as the 

 preceding. 



Chelipeds heavy ; four or five strong teeth on inner margin of merus ; 

 a very small tooth at end of outer margin; inner spine of carpus equal 

 to proximal spine of manus; outer spine of carpus small; one superior 

 spine on manus situated at distal fourth. A very short blunt spine at 

 posterior distal angle of merus of swimming leg, followed by a row of 

 spinules on distal margin. Outer margin of male abdomen sinuous. 



Age variation. — In the young (13 mm. long and under) the front is 

 more advanced than in the old, the teeth are not spinous but lobiform 



Figure 10.— Portunus (Achelous) 

 spinimanus, male (61277), outer 

 maxiluped, x3 



" Professor Verrill unfortunately compared his type material with the "tres-jeune" figure of A. Milne 

 Edwards, which is copied in the "Decapod Crustacea of Bermuda," with the caption "about M nat size." 



