63 



4080 

 ~4" • 

 4107 



4 

 4108 



33 73-3397 

 9 



5468 



10 



36. PoTAMON (Acanthotelphusa) wood-masoni, Eath])un. (Fig. 50.) 



Puratelpkusa edwardsi, Wood-Mason, Proc. Asiatic Soc, Bengal, 1875, p. 231, and Ann. Mag. Nat. Hist. 

 (4). XVII., 1876, pp. 121, 122. 



Potamon(Pamfiilphus(t)wood^nasoni, Mary J. Rathbun, Nouv. Archiv. du Museum (4), VII.. 1905, p. 262 

 {ulii si/non.), pi. xii., fig. 12. 



Miss Rathbun, assuming Paratelphusa to be a subgenus of Potmnon, 

 and being confronted with the difficulty that another species (of another 

 subgenus of Potamon) had ah'eady a right to the name edwardsi, changed the 

 name of the species now under consideration to wood-masoni. 



Miss Rathbun's procedure is not affected by the fact that Paratelphusa 

 (type: P. tridentata, Edw.) is a quite distinct genus, because "Paratelphusa" 

 edwardsi is still included, as a species of the subgenus Acanthotelphusa, in the 

 genus Potamon. 



If Acanthotelphusa should at any time be separated from Potamon, the 

 name edwardsi may be resumed for the present species. 



Carapace fairly broad, convex, but with an uneven surface ; its length is 

 from three-fourths to seven-eighths its greatest breadth (measured to base of 

 marginal spines), its depth is about half its length. The frontal region and the 

 antero-lateral corners of the carapace are more or less granulous, and there are 

 many fine short wrinkles dorsal of the fairly well-defined postero-lateral borders. 



Cervical groove deep-graven where it defines the posterior lobe of the 

 mesogastric area, and fairly clean-cut where it breaks the post-orbital crests 

 (at the usual point in hue with the inner angle of the orbital tooth), but 

 elsewhere broad and superficial. 



All the regions of the carapace — gastric, branchial, cardiac, and the paired 

 facets of the pree-cardiac — are well marked out, and the mesogastric areola is 

 defined in much of its extent. 



Front in the adult much more than one-third the greatest breadth of the 

 carapace (measm-ed to base of marginal spines), little deflexed ; its sides 

 convergent and dorsally convex ; its edge rather sharp, almost smooth, and 

 very obscurely bilobed. Oi'bits broad, the lower border sinuous, crenulate, and 

 separated from the external orbital tooth by a gap ; near the middle of the 

 upper border there is a faint break. 



