XIII. — THE FAUNA OF BRACKISH PONDS 

 AT PORT CANNING, LOWER BENGAL. 



Part IX. — A new species of Amphipoda. 



By the Rev. Thomas R. R. Stebbing, M.A., F.R.S., F.L.S., F.Z.S. 



In the year 1904 Professor Coutiere defined a new genus of 

 Amphipoda, with description and figures of the tj^pical species, 

 Grandidierella mahafalensis. The specimens described had been 

 collected two or three years earlier by Mons. G. Grandidier in 

 Madagascar. They came from the Lake Tsimanampetsotsa in 

 a previously unexplored region of the Mahafah^ country. The 

 lake in question is a long lagoon-like depression between latitude 

 24° and 24°3o' S. and in longitude 44° E., about six miles from 

 the west coast, and no longer possessing communication with 

 the sea. Its salinit}^ varying with the rainfall, is greater than 

 that of the sea during the dry season, and its fauna appears to 

 be very poor (Coutiere, loc. cit. infra). 



Professor Coutiere expressed an expectation that marine 

 examples of his singular new species would be forthcoming on the 

 west coast of Madagascar. This discovery has apparently not 

 yet been made, but what has actually happened is perhaps of 

 even greater interest. For the species about to be described, 

 from brackish ponds in Lower Bengal, displays the very closest 

 relationship to the one so recently found in a salt lake of Madagas- 

 car. Their differences may be considered to prove that the two 

 species have been for a long time isolated one from the other. Yet, 

 whatever the interval in chronology, the vast intervening space of 

 ocean has left unobliterated and in fact unobscured the evidence 

 of a common ancestry. 



That the two species have become clearly distinct will pres- 

 ently be shown b}^ characters of the antennae, upper lip, mandibles, 

 and gnathopods. Mons. Coutiere has, in an interesting manner, 

 compared his genus and species with Dryopoides, Stebbing; Un- 

 ciola. Say.; Chevreuxius grandimanus, Bouvier ; and Camacho 

 hathyplous, Stebbing. The last-named species, reported in the 

 "Challenger" dredgings to have come from a depth of 1,100 

 fathoms, has since been dredged off South Africa in 47 fathoms. 



Fam. COROPHIID^. 



1906. CorophiidcB, Stebbing, Das Tierreich, " Amphipoda Gam- 



maridea," Lieferung 21, pp. 662, 739. 



In the key to the genera of this family supplied under the 

 foregoing reference, M. Coutiere's genus, with which we are 



