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Show 716 SURGEON F. D A Y O N T H E [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 Clarias. 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 Cyprinidee 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 entirely enclosed in a bony capsule (Cobitidina) ; or absent (Homa-lopterina). From the opportunity I have had of obtaining specimens 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 arrangement 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 divisions 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 Museum Catalogue, to have escaped Dr. Giinther's attention. In vol. v., 277 pages are filled with an account of the family Siluridce 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 Cryptopterus, 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 possibility of its being supposed that I wish to create any erroneous impressions respecting Dr. Giinther's valuable ichthyological writings (see Zool. Eecord for 1869). Nothing is further from m y wish, which is to obtain facts, no matter who the author may be, and, if possible, to take nothing on trust from any naturalist, however excellent an observer he is, when I can examine into the matter myself. |
