ORAL GESTATION IN THE GAFF-TOPSAIL CATFISH, FELICHTHYS FELIS.
In a previous paper (Gudger, 1916) I have given in some detail the story of how I came to rediscover the habit of oral gestation in the gaff-topsail catfish, Felichthys felis (plate i, figure 1). In order to give the facts contained in this paper their proper setting, a brief resume of the data contained in the previous article will here be set forth.
In the summer of 1906, while at Cape Hatteras, North Carolina, Mr. N. F. Jennett, who operated a pound-net fishery in Pamlico Sound at that place, told me that in looking over the catch of his net on the previous day he had found a number of flat-whiskered ocean catfish, and that in handling these he had found in his hands a number of young. However, he was unable to say whether these had come from the mouth or the vent. At that time I was working in the Beaufort Station of the United States Bureau of Fisheries engaged in research on the embryology and breeding habits of fishes, so on my return I at once began to look up the literature as to habits of catfishes. I found that while there was a considerable literature on oral gestation in catfishes, certain rather definite con clusions were held that the smaller ocean catfish (Galeichthys milberti), also found at Beaufort and well known to me, is ovo-viviparous. Further, dissection of female gaff-topsails showed that the hinder part of each ovary, and especially the duct leading therefrom, was laid in plicated folds highly vascularized, in which it seemed possible for eggs to be held and nourished until hatched. However, on talking the matter over with a number of well-informed fishermen of Beaufort, I found that it was well known that the gaff-topsail carries in its mouth its eggs and even the larvae after hatching. One man put it that he "had seen the sea-cat spit its eggs out of its mouth." Unfortunately the breeding season was past and it was impossible to investigate these conflicting reports by study of the fish; so it was necessary to let the matter stand over until the next summer.
At the beginning of the season at Beaufort in 1907, difficulties were had in collecting early material and in fini -hing my observations on the breeding habits and embryology of another fish; hence it was not until June 22 that it was found possible to make a trip for catfish. In the Narrows of Newport River, at Rockfish Rock hauling-ground, a big catch of Felichthys was made. Thirty-two males carrying eggs were measured, and probably as many more were relieved of their oral burdens. Some half dozen of these were dissected and without exception all were found to be males. A large number of eggs was obtained, estimated at between 200 and 300, the greatest number taken from one fish being 26. These eggs were held loosely in the mouth, which was enlarged by a distension downward of the hyoid region and outward of the branchial arches, as shown in figures 2 and 3, plate'. Some of these eggs are shown in figure 8, plate in. Figure
7, plate in, is a photograph of the mouth of one of these fish with the eggs in situ. Attention is called to the extraordinarily distended mouth and to the great size of the eggs. One of these has two embryos.
Other trips were made during the summer of 1907, and scores of fish and hundreds of eggs were taken. Many observations and measurements of the adults were made; and much study was given to the eggs and larvie, which were kept alive with considerable diffi culty in aquaria in the laboratory. The result of all this work was the definite establishment of the fact that the male of the gaff-topsail catfish takes the recently spawned and fertilized eggs into his mouth and there nurses them until they are hatched and until the young are able to care for themselves.
During the summers of 1908, 1909, 1910, 1911 and 1912, the search for gaff-topsails was assiduously continued and no effort was spared to capture breeding males in the hope that early stages in the devel opment of the eggs might be obtained. These efforts were attended by few successes and many failures. The failures in the seasons of 1908 and 1912 are mainly to be attributed to unprecedentedly heavy rainfall in the Beaufort region towards the close of May. These rains so freshened the water at the head of Newport estuary as to drive the catfish into the lower and broad stretches of the river, where it was found impossible to take them (despite almost daily seinin' gs) at localities previously favored by the fish.
However, all the failures do not have so simple an explanation, for the fishermen, taking all possible precautions, made haul after haul in "holes" where recently or in previous seasons we had made fine catches, but the net came in with no catfish or at best with a few females or non-breeding males. In 1911, I even went so far as to make two trips to Beaufort; the first covering the time from May 13 to 18, the second for the season beginning May 25. The first time I was too early, the breeding not having commenced; the second time too late, the eggs having been laid during the interim.
These various failures were all the more regrettable because in the summers of 1908 and 1910, thanks to a grant from the Carnegie Insti tution of Washington, an artist was at hand to make drawings' for 'The drawings reproduced in this paper in figures 1, 2 and 3, plate i; and 9, 10, 11, 12 in plate iv, were made by Mr. E. A. Morrison under this grant.
the embryology of the fish. However, the work went on, and grad ually the series of eggs was pushed both forward and backward until now there is a complete series illustrated by photographs or drawings from invagination to the adult embryo.