716 SCRGEON F. DAY ON THE [Dec. 5, 



tions will be necessary, by all who consider a natural arrangement 

 preferable to an artificial one. 



During the past year I have examined as many Indian Siluroids 

 as I have been able to obtain in order to discover the character of 

 their air-vessels* — a subject which was commenced by Dr. Taylor of 

 Dacca in the ' Gleanings of Science' (vol. ii. 1830), a paper which I 

 only obtained for the first time in September 1871. Cuv. and Val. 

 have also some remarks on the air-vessels of Saccobranchus and 

 CI arias. 



Having in 1869, whilst in Orissa, discovered that the air-vessel of 

 Gagata typus, Bleeker, possessed a bony capsule, and since then 

 that several other Siluroids had this organ similarly protected, I 

 proposed to obtain, if possible, species of every Indian genus, in 

 order to institute a general examination of those of the family. 



The Cyprinidce of India are divisible into three subfamilies, one 

 of the chief characteristics of which are : — first, the air-vessel free 

 in the abdominal cavity, elongated, and with a transverse constriction 

 (Cyprinina) ; or divided into two lateral portions, partially or en- 

 tirely enclosed in a bony capsule (Cobitidina) ; or absent (Homa- 

 lopterina). From the opportunity I have had of obtaining speci- 

 mens of all the Indian freshwater genera, excepting Chaca, I have 

 now been enabled to ascertain the position and shape of this organ 

 in the Siluridce. 



A far wider acquaintance with all the known genera of this family 

 is desirable before any definite conclusions can be arrived at ; but 

 sufficient materials exist in India to show that the present arrange- 

 ment can hardly be continued. 



In the Indian freshwater Siluroids (and for the sake of rendering 

 this paper more complete I include those marine genera which ascend 

 rivers for the purpose of obtaining food) there are two distinct divi- 

 sions of air-vessels — those which are not enclosed in bone, and those 

 which are. 



Of those with the air-vessel not enclosed in bone we have Akysis, 

 Hara, Macrones, Rita, Arius, Batrachocephalus, Osteogeniosus, 



* This subject appears, if one may form an opinion from the British Mu- 

 seum Catalogue, to have escaped Dr. Giinther's attention. In vol. v., 277 pages 

 are filled with an account of the family Siluridee and the species composing it ; 

 but I only observe the air-vessel alluded to four times, as regards the Siluroids 

 of India or the Malay archipelago : — first, that if present in the order Physo- 

 stomi, it has a pneumatic duct (p. 1); secondly, that it is generally present in 

 the family Siluridce, communicating with the organs of hearing and by means 

 of the auditory ossicles (p. 2) ; whilst at p. 38, in the definition of the genus 

 Cryjttopterus, it is observed, "air-bladder transparent through the sides of the 

 body;" and at p. 40, of C. limpok, "this species appears to have the place 

 behind the head, where the air-bladder is seen through the transparent skin, of 

 a dark colour during life." I allude to the above in full to obviate the possi- 

 bility of its being supposed that I wish to create any erroneous impressions re- 

 specting Dr. Giinther's valuable ichthyological writings (see Zool. Eecord for 

 1869). Nothing is further from my wish, which is to obtain facts, no matter 

 who the author may be, and, if possible, to take nothing on trust from any na- 

 turalist, however excellent an observer he is, when I can examine into the matter 

 myself. 



