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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
have in these fishes a mouth gestation. In the mass of eggs with which the mouth is filled I have 
occasionally found the eggs, rarely more than one or two, of another species. The only way in which 
their presence may be accounted for, it seems to me, is by the supposition that while feeding the eggs 
are disgorged, and as these fishes are gregarious in their habits, when the ova are recovered the stray 
egg of another species may be introduced into the mouth among those which naturally belong there.” 
One of the earliest accounts of this curious habit which we have seen is that by Dr. Gunther* in 
which he says, referring to specimens of Arbus fissus from Cayenne received from Prof. R. Owen: 
“These specimens having had the cavity of the mouth and of the gills extended in an extraordi- 
nary manner, I was induced to examine the cause of it, when, to my great surprise, I found them filled 
with about twenty eggs, rather larger than an ordinary pea, perfectly uninjured, and with the embryos 
in a forward state of development. The specimens are males, from 6 to 7 inches long, and in each the 
stomach was almost empty. 
“Although the eggs might have been put into the mouth of the fish by their captor, this does not 
appear probable. On the other hand, it is a well-known fact that the American Siluroids take care of 
their progeny in various ways; and I have no doubt that in this species and in its allies the males carry 
the eggs in their mouths, depositing them in places of safety, and removing them when they fear the 
approach of danger or disturbance.” 
The following extract is from an interesting article “On the air-breathing fish of Ceylon” by 
Rev. Principal Boake, published in the Journal of the Ceylon Branch of the Royal Asiatic Society 
for 1865-66 (1866) pages 128-142, the extract occupying pages 138-142: 
“ Having occasion to visit Caltura periodically, I was told on one of my visits of a fish which is 
caught at certain seasons in very large quantities, and which has the singular habit, when held up by 
the tail, of emitting from the mouth a quantity of eggs. So great is the number thus emitted that 
when many fish are captured the eggs are eagerly collected from the bottoms of the boats and carried 
away to be fried, and are greatly relished by the villagers when so prepared, while the fish themselves, 
being too numerous to be consumed in their fresh state, are salted and dried, and often form an 
ingredient in the curries which appear at our tables. 
“The description which I received of the manner in which the eggs are procured seemed to point 
to the conclusion, universally believed by the natives, that the regular mode of bringing forth their 
young is, in the case of these fish, through the mouth; a fact which seemed to me to be so singular 
that I determined to stay a day or two longer at Caltura when I next visited it, for the purpose ol 
investigating the circumstances which seemed to indicate so singular a conclusion. 
“The result of my investigation was, as might have been expected, that I ascertained that the 
circumstances had not been fully or accurately observed, and consequently that the conclusion to which 
they pointed was erroneous; but I, at the same time, satisfied myself of a fact in the natural history of 
those fish, which will perhaps be regarded as but little less extraordinary than their novel mode of 
parturition would have been, if it had been established as true, and which, as Ceylon has acquired 
some notoriety for marvelous stories respecting its zoology, I should feel some hesitation in stating, 
were it not that, in addition to the abundance of unexceptionable testimony, I was able to procure 
specimens illustrating the whole extraordinary process. 
“These fish produce their eggs in the first instance very much in the same manner as other 
inhabitants of the waters do, with this exception, that the eggs seem to come to maturity in batches 
of ten or twelve. Bottle No. 1 will illustrate this. It contains the roe of one out of a large number of 
fish that I examined. You will perceive that, besides eight or ten large eggs, there is a whitish mass, 
which, on being closely examined, will be found to consist of other eggs of very minute size; the differ- 
ence in size between those which are ready for emission and the others which are immature being 
very remarkable. The strange fact, however, is that the large eggs on being emitted are immediately 
taken up, either by the fish that has laid them or by another of the same species, and, not swallowed, 
but kept in the mouth until they are hatched and the fry are able to take care of themselves, a period 
of some weeks, during which it is impossible that the fish, which is swimming about with so extraor- 
dinary a mouthful, can swallow any food except such small nutritious particles as may be floating 
about in the water. When these fish first make their appearance at Caltura, in the beginning of the 
* Catalogue of the Fishes in the British Museum, by Albert Gunther, v, 1864, p. 173. 
