3895. PROCEEDINGS OF THE NATIONAL MUSEUM. 353 



intranieciial region is about one-lialf its anterior widtli,^ The frontal or 

 interantennal teeth are two, triangiihir, acute, with faint indications of 

 two others on their oblique inner margins (Phite XXIV, fig. 1). The 

 median subfrontal sj)ine is conical and strong. The inner supraorbital 

 tooth is broad and bilobed, the lobes obtuse, the outermost very promi- 

 nent. The adjoining fissure is ch)sed except at the anterior extremity, 

 where there is a shallosv V-shaped opening. The lateral teeth are con- 

 cave on both margins and acuminate. Lateral spine in males from three 

 to about four times the length of the ])receding tooth.- Inner suborbital 

 tooth acute. Penultimate seguient of abdomen of male (Plate XXY, 

 tig. 1) much constricted in its proximal half, widening at both extremi- 

 ties. Terminal segment obtuse, lateral margins convex proximally, 

 slightly concave or straight distally. Api^endages of first segment^ 

 (Plate XXYl, fig. 1) reaching nearly to or beyond the extremity of the 

 abdomen, near together for their proximal half, with only a slight out 

 ward curve; distal portions widely divergent except at tips. The 

 abdomen of the adult female (Plate XXVII, fig. 1) is very broad, the 

 margins of the last three segments separately convex; terminal segment 

 longer than wide. Costa^of carpus and manus with depressed granules 

 or often almost smooth to the eye. 



Medium- sized specimens. — Carapace narrower than in adults; gran- 

 ules more <listinct, especially on the anterior half. Frontal teeth less 

 acute. Antero-lateral teeth broader, their margins more or less convex. 

 Lateral spine a little more than twice the length of preceding tooth. 

 Inner suborbital tooth broader, obtuse. Cost* of car])us and manus 

 more distinctly granulate. 



In very young males the abdominal appendages are nnich shorter, 

 reaching only to the middle of the penultimate segment. 



Size. — Adult males vary in width from (5^ to 7| inches; adult females 

 from 5 to 7 inches. 



'The transverse dimension of tlie intramedial region, or that division of tlie gastric 

 region posterior to the second graunhite ridge, I have designated as its width. Ord- 

 way does so under C ioxotes, but uses the opposite term under C. ortiattis. Thus the 

 intramedial region of both lie describes as long and narrow, which is misleading, the 

 two species being entirely different in this respect. 



'^Measurements are made from the tips of the spine and tooth to the inner end of 

 the intervening sinus; thus the spine is measured on its anterior margin, the tooth 

 on its posterior margiu. 



•'In both sexes of Callinectes the first abdominal segment is almost entirely concealed 

 beneath the carapace; thus the abdomen in the male consists of five segments, the 

 third, fourth and fifth normal segments being coalesced, the first and second being 

 furnished with appendages. In the female there are seven segments, the second, 

 third, fourth, and fifth with appendages. In Plates XXV and XXVIl the first two 

 segments are not shown. 



Proc. X. M. l>r> L>3 



