1918.] Stanley Kemp : Devapoda nj the Inle Lahe. 101 



near Fort Stedmaii the whole of the body was more or less darkened 

 with oreen clironiatophores and was sometimes almost black. A pale 

 mid-dorsal line was nsnally j)resent, and sometimes white specks could 

 be detected on the thorax, abdomen and telson. In paler individuals 

 there was a small dark spot at the base of each pleopod. The finders 

 of the chelae were darkened, but the bunch of hairs at the tip was often 

 white. Individuals from the He-Ho stream, the water of which has 

 a ])eculiar blackish colour owinu to the lar,<^e amount of frauments of 

 carbonized ve.uetation it contains, were rather dark Init had three parallel 

 colourless bars slanting alonu each side of the carapace. There was a 

 ])ale cross-bar on each al)dominal segment and a colourless mid-dorsal 

 line."" 



POSTSCRIFTUM. 



Acanthopotamon, 



nom. nov. for Acanthotelphusa Alcock nee Ortmann. 



While this paper was still in the press Caiman published an account 

 of Potatiton {Pofanwnautes) ivarreiii,'^ a new river crab from the Trans- 

 vaal. The affinities of this species, which are discussed by Caiman, 

 throw nmch liuht on the position of Ae<v)it}iotelphusa. 



P. (Potamonautes) warreni has an extremely close affinity with the 

 common South African P. (P.) perlatum, differing from that species 

 only in the fact that the granules of the antero-lateral margin are re- 

 placed by spiniform teeth. The species thus affords, in the subgenus 

 Potamonautes, an instance of evolution exactly parallel to that which 

 I believe to have occurred on at least two independent occasions in the 

 subgenus Potamon, viz. in P. (P.) s]ie)isiense and P. (P.) aeaiithieuni 

 (see p. 85). 



As Caiman has remarked P. [Potanionautes) irarrem on any of the 

 current schemes of classification would be separated generically or sub- 

 generically from P. (P.) perlatum. Were it not for the proofs of its 

 affinity that Caiman has brought forward, it is almost certain that it 

 would have been referred to AeanthoteJphusa, for it closely reseml)les 

 P. [Acanthotelphusa) nilotieum in the character of the antero-lateral 

 margin. 



There is, as Caliuan has hinted, reason for the belief that P. nUo- 

 tieum has originated, in much the same way as P. ivarreni, from some 

 East African species with normally constituted antero-lateral border. 

 But, however this may l)e. it is clear that its affinities are not with the 

 well-defined group of Asiatic species to which Alcock has applied the 

 name Acanthotelphusa. Since P. nilotieum. is the ty])e of the latter 

 subgenus, it is evident that a new name is necessary for the Asiatic 

 forms. I suggest Acanthopotamon, distinguished fiom Potamon s.s. 

 by two characters, — the antero-lateral borders of the carapac<» are cut 

 into three or four large teeth,- and (ii) the upper bolder of the meius of 

 the chelipedes bears a sub-terminal spine. 



1 Caiman, Ann. Mag. N,,l. Ili'^l. (9), T, p. 2:U (litlS). 

 * Exclusive of the external uil)it;il tuotli. 



