lOO' SMITHSONIAN MISCSI.LANEOUS COLLi;CTIONS 



prominent. Chelipeds moderately elongated ; meros serrulated along 

 the angles ; hand smooth, oblong, a little inflated within ; fingers 

 gaping, evenly denticulated within; tips excavated internally, with 

 sharp corneous outer edges for nipping or cutting. Ambulatory 

 feet long, smooth, pubescent at base, the first and last pairs reaching 

 only to the penult joints of the middle pairs, which joints are every- 

 where thickly pubescent ; dactyli somewhat compressed, five-sided 

 or quinquecostate, tapering to slender sharp extremities. Abdomen 

 with all the segments distinct; terminal joint abruptly smaller than 

 the penult. The margin of the sternum is raised into a crest around 

 the terminal abdominal segment. Dimensions of the carapax: 

 Length, 0.46 ; breadth, 0.61 inch. Length of ambulatory feet of the 

 second pair, 1.38 inches. 



This species differs from M. distmctus in the lobation of the infra- 

 orbital margin, and from M. indicus in its narrov^^er carapax and the 

 distinct segmentation of the abdomen. 



Found in Hongkong Harbor. 



Genus ILYOPLAX Stimpson 



Body tetragonal, very thick. Carapax very little indurated. Front, 

 antennae, antennulse, and orbits nearly as in Macrophthahnus ; the 

 front is, however, broader than in that genus. Eye-peduncles suffi- 

 ciently long. External maxillipeds saillant, not gaping; exognath 

 concealed, palpigerous ; meros of endognath large, longer than broad, 

 and longer than the ischium; ischium ornamented with an oblique, 

 almost transverse piHferous line placed close to the commissure of 

 the meros; palpus rather prosarthroid than exarthroid, projecting as 

 in Macrophthahnus. Chelipeds equal. Ambulatory feet rather stout, 

 those of the second pair conspicuously the longest; meros- joints with 

 membranaceous sides, or tympana occupying the entire faces ; dactyli 

 very small and slender. Sternum and male abdomen nearly as in 

 Macrophthalmus. 



This genus, although properly belonging to the family in which it 

 is here placed, in its thick body, soft structure, and tympanum-like 

 surfaces of the thigh- joints, will form a connecting link between the 

 Macrophthalmidse and the Dotillidee. 



It is an inhabitant of brackish waters on the shores of southeast- 

 ern Asia. 



157. ILYOPLAX TENELLA Stimpson 

 Ilyoplax tenella Stimpson, Proc. Acad. Nat. Sci. Phila., x, p. 98 [44], 1858. 



Carapax nearly quadrangular, length to breadth as i : 1.54- An- 

 tero-lateral angles obtuse. Sides slightly convex and bordered by an 



