312 MR. G. E. DOBSON ON the [May 19, 



Tschudi dans la description de la M. agilis. Le poil des parties 

 inferieures est unicolore. Lesgriffes sont blanchatres. Dimensions 

 en millimetres : 



t. ?. 

 Long, depuis le nez jusqu'a la naissance de la 



queue 270 2/0 



„ de la queue avec le poil 185 175 



„ de la queue sans poil 150 1 73 



„ de la tete fiO 60 



„ du tarse avec les griffes 51 51 



C'est l'espece la plus voisine de la M. frenata du Mexique ; la 

 grandeur est presque la meme, ainsi que la proportion de la queue, 

 qui est aussi presque egalement velue, terminee en pointe et non pas 

 en pinceau comme dans la M. erminea. 



Saus doute c'est 1' animal mentionne par Tschudi*, ildit : "Nous 

 supposons que plusieurs differentes especes s'y trouvent, car nous 

 avons vu plusieurs fois une belette pres de deux pieds de longueur, 

 sans avoir eu le bonbeur de la tuer. Les renseignements des Indiens 

 confirment notre supposition." Notre animal est plus petit, car il 

 n'a que 18 pouces, mais Tschudi a pu exagerer sa grandeur en 

 comparant avec M. agilis. 



3. Notes on the Respiration of some Species of Indian 

 Freshwater Fishes. By G. E. Dobson, B.A., M.B., 

 C.M.Z.S., F.L.S. 



[Keceived April 20, 1874.] 



The following notes on the respiration of some species of Indian 

 freshwater fishes were derived from experiments made in the months 

 of April, May, and June last year upon several specimens from the 

 river Hooghly, near Calcutta. The number of species examined was 

 eleven, representing six families — namely, Siluridse, Symbrauchidse, 

 Cypriuidse, Labyrinthici. Ophiocephalidse, and Mastacembelidse. 



Previous observers f of the habits of the freshwater fishes of tro- 

 pical countries had remarked that some species required atmospheric 

 air directly for the purpose of respiration, and if prevented from 

 obtaining it were suffocated, precisely as land animals would be. To 

 such species the term "aerial" or "compound breathers" has been 

 applied, in contradistinction to that of " water-breathers," which is 

 applicable to most species of fishes. 



* Fauna Peruana, Saugeth. p. iii. 



t To avoid entering upon an account here of what has been observed on the same 

 subject previously, it will be sufficient to refer to Mr. Boake's paper on the fishes 

 inhabiting the Ceylon marshes, published in the Journal of the Ceylon Branch 

 of the Boyal Asiatic Society, 1865, and to Mr. Francis Day's paper entitled 

 " Observations on some of the Freshwater Fishes of India," in P.' Z. S. 1868, 

 pp. 274-288, in which, besides an account of many most interesting and original 

 experiments on the respiration of these fishes, the investigations of previous 

 observers are described or referred to. 



