104 BULLETIN 152, UNITED STATES NATIONAL MUSEUM 



Description. — Carapace of adult male from 2% to 2^2 times as 

 broad as long, moderately convex; granules of medium size, crowded 

 on the cardiac and inner branchial regions, scattered and faintly 

 marked on the anterior half of the carapace. Length of intramedial 

 region about one-half or a little less than one-half its anterior width. 

 Frontal teeth two, broadly triangular, subacute, extremities almost 

 rectangular; faint indications of a median pair of denticles on their 

 oblique inner margins sometimes present; median subfrontal spine 

 conical and strong. Inner supraorbital tooth broad, faintly biden- 

 tate, less advanced than the front; of the superior fissures the outer is 

 shorter than the inner, both are closed except at anterior extremity 

 where there is a shallow V-shaped opening; outer tooth elongate- 

 triangular, acute; inner suborbital tooth acute. Lateral teeth 2 to 8 

 acuminate, concave on both margins; lateral spine in males from two 

 to about four times the length of preceding tooth. Costae of wrist 

 and hand marked with depressed granules, often almost smooth to 

 the eye; lower costa obsolete on greater part of palm. 



Penultimate segment of male abdomen much constricted in its 

 proximal half, widening at both extremities; terminal segment elon- 

 gate, obtuse, lateral margins convex proximally, slightly concave or 

 straight distally; appendages of first segment reaching nearly to or 

 beyond the extremity of the abdomen, approximate for their basal 

 half, with only a slight outward curve, distal portions widely divergent 

 except at tips. Abdomen of adult female very broad, margins of 

 third, fourth, and fifth segments separately convex; terminal segment 

 longer than wide. 



Age variation. — In small and medium sized specimens the granules 

 are more distinct on anterior half of carapace and on costae of wrist 

 and hand, the antero-lateral teeth broader, their margins more or 

 less convex, inner suborbital tooth broader and obtuse, abdominal 

 appendages shorter than in the old. 



Color. — Grayish or bluish green of varying shades and tints 

 relieved by more or less brilliant red on the spines of carapace and 

 on the fingers. (Hay and Shore.) Occasional examples of albinism 

 have been noted, either a claw (23840) or a wholly white crab 

 (Maryland). 



Size. — Adult males vary in width from 6M to 8% inches; adult 

 females from 5 to 7 inches. Male (19051), total length of carapace 

 75.4, width of same 178, width at anterior base of lateral spine 139.2, 

 fronto-orbital width 62.6, width of front 19.6 mm. Male (59885). 

 total length of carapace 93.6, width of same 223, width at anterior 

 base of lateral spine 169, fronto-orbital width 76, width of front 

 23 mm. 



Habitat. — Muddy shores to deep water; brackish water of estu- 

 aries, and occasionally in fresh water. Common; used abundantly 

 for food. 



