330 FISHES 



is used for isinglass, its oil for tanning. It spawns in November, 

 December, and January, and according to von Jhering comes 

 from the ocean to the river for this purpose. The eggs are 

 large, measuring 18 mm. or nearly f in. in diameter, and 

 males with eggs in the mouth do not take the hook, which 

 indicates that they take no food while in this condition. In 

 1857, Dr. Wyman investigated this mouth-gestation in several 

 species of Siluroids at Paramaribo in Dutch Guiana ; the 

 species belonged to the genus Bagrus or one nearly allied to it. 

 His account contains some particulars in addition to those 

 given above. The mouth and branchial cavity were very 

 much distended by the eggs which were twenty to thirty in 

 number, the gill-cover being round and swollen. Dr. Wyman 

 observed that the hatched larva or foetus found in the mouth 

 in some cases weighed more than the undeveloped egg, and 

 concluded that it had grown at the expense of some other 

 nutriment than that derived from the yolk, so that there is 

 some possibility that the eggs are not merely protected in the 

 mouth cavity but also absorb nutriment from its secretions. 

 Galeichthys is an African genus, and Mr. Boulenger received a 

 specimen from Port Elizabeth with thirty eggs in its mouth, 

 but does not say whether the sex was male or female. 



Species of Cichlidae are found in Asia, Africa, and America, 

 but are absent from Australia. In some species it is stated 

 that the male carries the eggs, in others the female, but Mr. 

 Boulenger states that in the African species it is certainly the 

 female only which carries out the incubation, all specimens- with 

 eggs in the mouth being of this sex. In some cases at least the 

 parent not only incubates the eggs in its mouth but also guards 

 the young after hatching, and receives them into its mouth 

 again when any danger threatens them. Thus Dr. Reinhold 

 Hensel, writing of observations in South Brazil in 1870 and 

 referring to a species called Geophagus scymnophilus, states that 

 in December the summer was too far advanced for him to see 

 the spawning process, but he frequently had opportunities of 

 observing the parent with a brood of young ; he says the parent 

 was probably the male but did not ascertain this with certainty. 

 In a shallow part of the stream near the bank a shoal of 20 to 30 

 young swim about while the old fish keeps watch at some little 

 distance. When alarmed the old fish swims to the shoal of 



