43 



and formiiif the convexity of a common curve with them. Post- orbital crests 

 prominent, with the edge distinctly defined. 



Male abdomen with the 6th segment twice as broad as long, and the 7th 



as long as broad. 



Antennules and antennae as in tumidmn. Mouth -parts differing from those 

 of tumidiim in that the merus of the external maxillipeds is quite as long as 



broad. 



CheHpeds as in tumidum, but the sculpture is crisper and the spine at the 



inner angle of the carpus is longer and acute. 



Legs long, the 2nd (longest) pair considerably longer than the chelipeds ; 

 in the 2nd and 3rd pairs the length of the propodite is more than twice its 

 breadth ; dactyli very long. 



Length of carapace Hths inch, breadth 1 A inch, depth f\ths inch. 



One of the specimens is an egg-laden female, the eggs being few and nearly 

 3 mm. in diameter. 



6952 Bm.„^^^ W.Theobald. ll,?, 6?. 



3 ■ 



^'^^'' Upper Tennasserim. J. Wood-Mason. 1 ? , 2 young. 



10 ■ ^* 



5496 Upper Tennasserim. J. Wood-Mason. 1 young ? (in-ob. this sp.). 



10 



22. PoTAMON (PotamonI) tumidulum, Alcock. (Fig. 6.) 



This species appears to be related to tumidum and turgidulum, but it differs 

 from them and goes near to the Potamiscus subgenus in having only a vestige 

 of a flagellum to the exopodite of the external maxillipeds. 



Carapace : length about four-fifths greatest breadth, depth half the length, 

 convex fore and aft. The cervical groove is well graven in all its course and 

 breaks the post-orbital crest at a point in the longitude of the inner limit of the 

 external orbital tooth. The mesogastric and epigastric areolse are distinctly, 

 if superficially, defined. The epibranchial regions are bisected by a strong 

 obUquely-transverse groove, and are again divided by an indistinct depression 

 that skirts the cervical groove. Antero-lateral region of the carapace rugulose ; 

 postero-lateral borders crossed by short faint ripples ; side-walls with almost 

 effaced ripple-markings. 



Front, in adult, less than a third the greatest breadth of the carapace, 

 strongly deflexed, its edge smooth ; broadly bilobed in a dorsal view. External 

 orbital tooth small, separated from lower border of orbit by a shallow gap. 

 Antero-lateral borders raised, crenulate ; epibranchial tooth distinct. 



Epigastric crests rugulose, more tumid than the post-orbital crests and 

 independent of and sHghtly in advance of them. Post-orbital crests broad, 

 blimt, rugose, with a coarse, ill-defined edge; they are cut by the cervical 



