28 Ratlibun Three New Species of Fresh-water Crabs. 



Carapace rather narrow, about four-fifths as long as broad, very con 

 vex in an antero-posterior direction, nearly level transversely in the 

 widest part. Surface granulate and punctate, anterior and antero-laterul 

 portions tuberculate or rugose. Cervical suture obsolete, except its poste 

 rior third. Postfrontal crest interrupted, tuberculate. Protogastric lobes 

 oval, depressed, in advance of the remainder of the postfrontal crest and 

 separated from it by a sulcus behind the inner angle of the orbit ; the 

 outer portion of the crest is concave forward and subparallel to the orbital 

 margin, and terminates laterally in an acute epibranchial tooth, 2 mm. 

 behind the orbital tooth. Behind the epibranchial tooth there is a 

 raised tuberculate and convex margin extending half-way back on the 

 carapace. The carapace is swollen laterally outside of and beneath this 

 margin. Front (fig. 2) about one-fourth the entire width of the carapace ; 

 lower margin straight, sides oblique. The median suture is not continued 

 in front of the protogastric lobes. Frontal and orbital margins strongly 

 rimmed. Superior orbital margin sinuous ; outer tooth broad, acute, 

 separated from the crenulated inferior margin by a deep rounded sinus. 

 Subbranchial regions crossed obliquely by short tuberculated rugse which 

 extend up to the postero-lateral margins. Suborbital region sparsely 

 tuberculated on its posterior half. 



The sides of the penultimate segment of the abdomen of the male are 

 convex; terminal segment with slightly sinuous margins (fig 3). 

 Maxillipeds (fig. 4) with merus as long as wide, outer margins oblique, 

 converging anteriorly. Chelipeds unequal in both sexes, very rough. 

 Outer surface of merus rugose ; margins with blunt teeth. Carpus rugose, 

 a very strong inner tooth with denticles beneath . Hands very rough on 

 the outer side, less so on the inner side. Fingers bent down, those of 

 larger hand gaping a little at base. Ambulatory legs long and narrow. 



Dimensions. Male, length 35.5 mm., width 44, width between margins 

 41.5, inferior width of front 10.4; female, length 30 mm., width 37.5, 

 width between margins 36, inferior width of front 9.5 mm. 



Type locality. Trong, Malay Peninsula ; Dr. W. L. Abbott, 1896 ; one 

 male, three females (U. S. Nat Mus. No. 20641). 



This species approaches nearest to P. pealianus (Wood-Mason) of Sib- 

 saugor, Assam, but is separated from it by a number of prominent charac 

 ters, viz., obliteration of cervical suture, swollen subbranchial area, elon 

 gate merus of the maxillipeds, slenderer legs, and narrower carapace. 



Potamon (Geothelphusa) levicervix sp. nov. 

 PL II, figs. 5-8. 



Postfrontal crest and cervical suture obsolete ; epibranchial tooth blunt ; legs 

 long and narrow. 



Carapace about three-fourths as long as broad, thick, very convex in a 

 longitudinal direction, and less convex although distinctly and regularly so 

 in a transverse direction. Surface smooth and punctate, with a few larger 

 depressions on the anterior half. Cervical suture obsolete. Branchio- 

 cardiac depressions deep. Postfrontal crest absent ; protogastric lobes in- 



