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Show 706 SURGEON F. DAY ON NEW INDIAN FISHES. [Nov. 4, diameter. Inside the mouths of several of the males of the Arius subrostralus. C. & V., A. gagora, H. B., A. sumatranus, Bennett, and Osteogeniosus militaris, Linn., were from 15 to 20 eggs; and it was evidently some of these which had been dropped into the boats and baskets. On examining the eggs, some were in an early stage of development, whilst in others the eyes of the embryo were very distinct, even the young could be perceived moving about. In the mouth of one of these fishes was a hatched fry, with the yolk-bag still adherent; and on cutting open other eggs it became evident that in a very short time the little ones would have emerged. These eggs filled the cavity of the mouth, and extended down as far as the branchiae. On dissecting a number of these specimens, there was an entire absence of food in the intestinal canal. The fishermen asserted that these adult fishes, which averaged about 11 or 12 inches in length, invariably carried about the eggs in their mouths until they were hatched. Every one of these were males; and the proportion captured was five to every female *. Next, the females came under examination. On tracing up the ovisacs it appeared that very large numbers of eggs existed in them, but not all of the same size. On the part furthest removed from the outlet the eggs were of full size, and about 50 in number, whilst other batches of much smaller size existed, evidently to take the place in due time of the larger ones when they had been deposited. The full-sized eggs were each attached to the inside of the ovisac by a pedicle of varying length, distinctly supplied with blood-vessels of a considerable size. No cicatrices could be detected showing that any eggs had burst into the cavity of the abdomen; and it would appear probable that they are extruded in the usual way, which idea is strengthened by the peculiar formation of the ventral fins. On looking at the conformation of the ventral fins of the males and the females, one is at once struck at the difference which exists in the two sexes f. The ventrals in the males are not enlarged ; but they are very considerably so in the females, reaching well over some of the first of the anal rays. They are also thickened by a deposit of fat, whilst the innermost ray has a large pad of fatty matter attached to its posterior margin. These fins can be expanded into a cup-like surface, the use of which is probably to receive the eggs as extruded. Perhaps the eggs as laid in batches are received into this receptacle formed by the ventral and anal fins, and may be here vivified by the male, who then removes them in his mouth, where they remain until hatched. Although the males at this interesting period appear to fast, the females do not do so, their intestines being found to be replete with food, doubtless a necessity for the due production of their eggs. * This is curious, as differing in the usual proportion of the sexes. In the Clupea pcdasah, C. & V., I found just the reverse obtained. t The comparative length of ventral fins in fishes of the above genera is not any guide to species, but merely to sexes. |