NO. 2030. NEW SPECIES OF CRABS— RATH BUN. 355 



This species is closely related to P. riedelii pilosa de j\Ian/ but differs 

 in several important particulars. The form of the maxilliped is very 

 different; the exognath is narrower, the ischiognath has not parallel 

 sides, nor is the merognath elongate, but broader than long; the palm 

 lacks the curved groove near the wrist which is characteristic of 

 riedelii ~ and r. pilosa; the abdomen is broader and less triangular, 

 the length of the sixth segment is less than half its proximal width. 



SESARMA (SESARMA) TIOMANENSE, new species. 

 Plate 31. 



Type-locality.— Fulo Tioman, Malay Peninsula; Dr. W. L. Abbott; 

 October 14, 1900; 1 female, ovigerous. 

 Type.—CsLt. No. 24806, U.S.N.M. 



Dimensions.— Femsile, length, 34.7 mm.; greatest width, at third 

 lateral tooth, 42 mm. ; width between orbital angles, 40 mm. ; width 

 of front at level of eyes, 21 mm.; extreme length of propodus of 

 cheHped, 35.2 mm.; superior length of same (spine excluded), 13.3 

 mm.; height of same (spine excluded), 19 mm.; length of movable 

 finger, 23.7 mm. 



Carapace very high, very convex antero-posteriorly ; hepatic, meso- 

 gastric, cardiac and intestinal regions bordered by deep grooves; 

 surface mainly covered with tufts of dark-colored bristles. The nar- 

 row part of the mesogastric region is traversed in its posterior haff by 

 a high, blunt median ridge, which is surmounted by a band of bristles. 

 Postfrontal lobes deeply separated, the median furrow much deeper 

 and wider than the outer furrows, which are continued backward to 

 the widest part of the mesogastric region; lobes of the inner pair 

 twice as wide as those of the outer pair; the inner lobes appear trans- 

 verse in dorsal view, but curve downward toward the middle in front 

 view; the outer lobes have an oblique edge, sloping downward to the 

 inferior angles of the front. The surface of the front below the lobes 

 is very shallow; the lower margin is cut into two broad lobes sepa- 

 rated by an equally broad sinus, while the outer angles are produced 

 outward and downward in a triangular and subacute tooth. 



Superior margin of orbit transverse, deeply sinuous. Three acute 

 lateral teeth, including the orbital tooth, each higher than the pre- 

 ceding, the second the longest, the thnd the shortest; margins den- 

 ticulate. Side margins of carapace arcuate. 



Epistome very deep, the lateral tooth of its lower border spiniform. 

 Merus of outer maxiUipeds considerably longer than ischium. 



Chelipeds slightly unequal, distmguished by their spinous margins. 

 Inner margin of ischium and merus armed with spines; instead of a 

 large tooth near the distal end of the merus there are two small 



1 In Weber's Zool. Ergebnisse einer Reise in Niederlandisch Ostindien, vol. 2, 1892, p. 323. 



2 Gnathograpsus riedelii A. MUne Edwards, Nouv. Arch. Mus. Hist. Nat., Paris, vol.'4, 1868 p 182 pi 

 27, figs. 1-5. 



