Crustacea Decapoda and Stomatopoda. 247 



Paratelphusa (Paratelphusa) incerta (Lanchester) . 



1905. Potamon (Paratelphusa) inceftus, Rathbun, Nouv. Arch. Mus. Paris (4), VII, p. 238 



(ubi syn.). 



Of this species Dr. Annandale obtained a single fine male, with carapace 55 mm. 

 in breadth, in the Botanical Gardens at Singapore. It was found on a wet day in a 

 rubber plantation, sitting at the edge of a burrow in the bank of an irrigation chan- 

 nel. 



Paratelphusa incerta is very closely related to the Sumatran P. maculata, de Man ; 

 but, so far as I am able to judge from the examination of a single specimen, is not 

 merely a variety of that species as suggested by Nobili.' Compared with a series of 

 P. maculata from Deli in Sumatra, the following differences are apparent : — 



(i). The carapace is broader and shorter: measured in the middle line the dis- 

 tance from the edge of the front to the cervical suture is conspicuously less than half 

 the greatest breadth of the carapace. In P. maculata these two measurements are ex- 

 actly the same. 



(ii). An imaginary hne joining the tips of the posterior epibranchial teeth is 

 situated rather further forwards than in P. maculata. 



(iii). The lateral extremities of the post-orbital crests reach a point only a little 

 in front of the middle of the foremost epibranchial tooth and are thus situated further 

 backwards than in the allied form. 



(iv). The external orbital angle is rather more obtuse and the two epibranchial 

 teeth project outwards more strongly. The distance between the extra-orbital angle 

 and the first lateral tooth is only a little greater than that between the first and 

 second lateral teeth. 



P. incerta is known only from Singapore and was originally described by Lanches- 

 ter from a specimen found in the Botanical Gardens. The individual recorded by 

 Lanchester from Borneo' has been referred by Miss Rathbun* to Nobili' s P. oxygona. 



Paratelphusa (Paratelphusa) germaini (Rathbun). 



1901. Potamon (Paratelphusa) sinense, lyanchester, Proc. ZooL Sac. London, p. 545. 

 1905= Potamon (Paratelphusa) germaini, Rathbun, Nouv. Arch. Mus. Paris (4), VII, p. 246, 

 (ubi cet. syn.), pi. xi, fig. 9. 



1906. Potamon (Paratelphusa) sex-punctatum, Manchester, Fasciculi Malayenses, ZooL, III, 



p. 129, fig. 2. 



Dr. Annandale found this species in abundance in ditches and ponds and at the 

 edge of the Tale Sap at Lampam, where the water of the lake is quite fresh. It was 

 common also at Singgora, but apparently does not enter the brackish outer portions 

 of the lake though it occurs in ditches containing water that is slightly saline. It 

 was also common in ditches at Patani and in pools on the sand near the sea. 



In a very old male, much overgrown with alga, the carapace is 56 mm. in breadth 



I Nobili. Boll. Mus. Zool. Torino, XVI, no. 397, p. 8 (1901). 



i Lanchester, Ann. Mag. Nat. Hist. (7), VI, p. 255, pi. xii, fig. 2 (1900). s Rathbun, loc. cit., p. 239. 



