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Method of Transfer of the Eggs

fish, mouth and catfish

METHOD OF TRANSFER OF THE EGGS.

On this interesting point nothing definite is known. In 1858 Green, and in the following year Wyman (1859), reported the finding of eggs of two species in the mouth of an oral incubating catfish of Guiana. From this they concluded that the eggs were disgorged in order to feed and later were taken up again. From this it is not a far cry to Goode's quotation from letters from Silas Stearns (Gill's revision of Goode's American Fishes, 1903) : "It (Galetichthys milbertz) breeds in summer, in June, July, and August. The spawn is deposited in a depres sion of the sand and impregnated with milt. One of the parent fish then takes the eggs in his mouth. . . . The eggs are carried in this position until the embryo fish are hatched." Whether this is an observation or a conjecture of Stearns's can not be said. However, the statement is very direct and positive. Smith (1907) quotes it as a fact, and it should be noted here that Stearns seems to have been a careful and accurate observer, and that he had Goode's full confidence.

However, Steindachner (1875), in describing Arius planiceps, a catfish from Panama, found that at the breeding season the innermost edges of the ventral fins of the female are developed so as to form a kind of pocket. He conjectured that the eggs are extruded into

this, fertilized by the male, and then taken into his mouth. He found a similar structure on the female of A. kessleri, the male of which is also a mouth brooder. Moreover, two years before this, Day (1873), writing of the Indian genera Arius and Osteogeniosus, had described precisely similar structures and had made an identical surmise.

The present writer has sought diligently to ascertain the method of transfer in the gaff-topsail catfish, but in vain. The fish are so large that it has not been found practicable to isolate them in pairs, and the water is too muddy at their breeding-grounds in Newport River for any observations to be made in the open. No structures like those described by Steindachner have been noticed on any female examined. The manner of transfer of the eggs in this fish is still a mystery.