144 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
others with the embryo very considerably advanced. The eggs were always in the mouths of males, 
and were not bruised, and none was found in the stomach. In the fifth volume of his Catalogue of 
Fishes in the British Museum* Dr. Gunther relates that, whilst examining some specimens of Arius 
fissus from Cayenne, presented to the Museum by Professor Owen, he was surprised to find their 
mouths and gill chambers distended with about twenty eggs rather larger than an ordinary pea. The 
eggs were perfectly uninjured, and the embryos in a forward state of development. These specimens 
were also males. 
“Again, Professor Agassiz, writing from the river Amazon, September 22, J865,f states that he had 
observed a species of Geophagus, G. pedroinus, a fish belonging to the family Chromidse, in which the 
mouth and a pocket-like pouch, formed by the superior pharyngians, contained a number of ova. How 
the eggs get into the mouth he is quite ignorant, but there they remain until the young are in a fit state 
to take care of themselves. In all the above cases the fish are denizens of the South American Continent, 
and, except the sjiecies described by Agassiz, belong to the Siluroid family. 
“The observations to which I shall now direct attention prove that this remarkable egg-carrying 
habit is not confined to certain species of fish dwelling in the New World, but is shared by some of the 
fish of the Old World also. In the month of April of the present year I received for examination, from 
the eminent botanist, the late Dr. Greville, some specimens of Siluroid fish, which had been sent him 
by the Rev. Bancroft Boake, of Ceylon. The specimens were accompanied by a copy of the literary 
supplement to the Ceylon Examiner, to which Mr. Boake had communicated ‘An account (dated April 
20, 1865) of some peculiarities in the habits of certain species of fish that are found in the waters of 
Ceylon.’ The most interesting portion of this narrative consists of an account of the habit of a fish 
caught at Caltura, in that island. When held up by the tail it emits from the mouth a quantity of 
eggs, which, when many fish are captured, are fried and used for food by the natives. The fishermen 
suppose that the regular mode of bringing forth the young is through the mouth, but Mr. Boake 
satisfied himself that the fish produce their eggs in the ordinary way, and that after being deposited 
they are immediately taken into the mouth, either by the fish that has laid them or by another of the 
same species, where they are kept until they are hatched. 
‘ ‘ The specimens given to me were two males and one female. The female had no ova in her 
mouth; but from the appearance of the abdomen it was evident that the ovaries were distended; and 
on opening into the cavity I found a large sac-like ovary on each side of the middle line. Each ovary 
measured 21 inches in length and extended forward almost as far as the pectoral fin, where it formed a 
rounded free end, whilst posteriorly it was somewhat constricted, and opened by an orifice common to 
it and its fellow immediately behind the anus. The ovisac contained a very large number of eggs in 
various stages of growth. Some were like minute granules, others, and these were very numerous, 
like medium-sized shot, whilst a third set equaled in size grapes or small cherries and very materially 
exceeded therefore the size usually attained by the eggs of osseous fish. These last, only six in number 
in each ovary, had evidently almost reached the full period of intraovarian growth. Each ovum 
was attached to the inner wall of the ovisac by an independent pedicle, the atrophy of which would 
necessarily precede the discharge of the egg. 
“The mouth and branchial chamber of one of the male fish were distended with 10 ova as large 
as those found in the ovarium, which were so closely packed together that water, or minute particles 
of food, could only pass backward to the gills or the oesophagus by filtering through the narrow 
interspaces between the eggs. In each ovum the development of the embryo had advanced so far 
that the eyes, chorda dorsalis, and cerebro-spinal nervous axis could without difficulty be distinguished, 
and from the ventral surface of the embryo numerous vessels were seen ramifying over the surface of 
the yelk. The embryos measured from one-half to seven-tenths of an inch in length. Only 1 of the 10 
eggs had sustained any injury, its investing membrane being ruptured, so that a portion of its contents 
had escaped. It is interesting to note that the palatine teeth of the fish are granular, so that their 
form is well adapted for permitting the retention of the ova in the mouth with a minimum of injury. 
“Mr. Boake’s observations show that the eggs are not placed in the mouths of the fish by the 
natives for purposes of deception, but that the instinct of the animal prompts it to take them into that 
cavity; and it is, as these specimens show, by the male, and not by the female, that this act is performed. 
In this respect this Cingalese fish agrees with those already described by Drs. Wyman and Gunther. 
* London, 1864. 
f Quarterly Journal of Science, p. 302, April, 1866. 
