PARENTAL CARE AMONG FRESH-WATER FISHES. 405 



Oral gestation or carriage of eggs wi^^hin the mouth of the parent 

 fish is practiced in a nuinljer of unrehited species. In Sihiroid cat- 

 fishes it is associated with enlarged size of the eggs, as in most Tachi- 

 surines and one of the Pimelodines {Conorhynchos), and is confined 

 to the males. The Malapteruroid, or electric catfish, is also said to be 

 an oral egg carrier. In other fishes the eggs of the egg carriers are 

 not essentially ditl'erent from those of normal habits, and many 

 related species do^ not have the peculiarity." Such Qg^^ carriers are 

 Cichlids of America (Geop/uu/us) and of Africa {7'Uapia, Tropheus, 

 EcUxhiH^ etc.), as well as sjjecies of the marine genus C hilodipterus^ 

 one of the Apogonids. 



It is especially noteworthy that among the Cichlids are exceptions 

 to the rule that the care taker is a male. In several cases it has been 

 verified that the Qgg carrier is a femal-i and presumably, of course, 

 the layer of the eggs. From evidence so far accumulated it would 

 seem that the sex of the care taker is coincident with sjjecific char- 

 acters, and that when the care taker is a female the male is not. At 

 least, in a receiit article (L'incubation buccale chez le TUapia (jalilaea 

 Artedi, li)04), J. Pellegrin showed that all four individuals of the 

 f.pecies exanuned which had eggs in the mouth were females, and he 

 could find no male egg carriers. Boulenger previously had found 

 eggs in the mouths of females only of T'dap'm nUotica and other 

 Cichlids of the genera Ecto<bis^ TropheiiK^ and Pelmafochromi.s. On 

 the other hand, the sex of the egg carrier of TUapia phihuider was 

 determined by so competent an authority as A. (iiinther to l)e male. 

 Further, Lortet named a Cichlid T'tJapia, paterfauiUiax^ which was 

 declared by Pellegrin to be specifically identical with T'dapia 

 ^'ononis. Lortet gave his name, because he considered the egg carrier 

 to be the male, while Pellegrin confirmed, by dissection, the sex of a 

 specimen of the same species to l)e female. Evidently, then, there is 

 necessity for further observations as to the sex of the ^gg carriers of 

 African, as well as the American, Cichlids.'' 



« The eggs of some of the ovigeroiis Cichlids are very large. According to 

 Boulenger (T. Z. S., XV, 18), " the mouth and pharynx of" a female TropJieits 

 moorii contained " foiu' eggs of very large size, the vitelline sphere measuring 

 4 millimetres in diameter, with an embryo in an advanced stage of develop- 

 ment. The eggs of > the fifteen-spined Stickebaek. hitherto regarded as the 

 largest Teleostean egg in proi)ortion to tlie size of the animal, measures only 

 o millimetres in diameter." The egg-earrying Tropheus was only aliout 4 in<-hes 

 long. 



6 The above remarks are left just as they were printed, l)ut on the same 

 day as the i)roof of this article was received from the printing otlice a " Fourth 

 Contribution to the Ichthyology of Lake Tanganyika." by G. A. I?oulenger, 

 fresh from the press, was also received, containing the much-needed " further 

 observations." Doctor Boulenger records that Doctor Cunnington. tiie latest 

 explorer of the ichthyology of the lake, had been " so fortunate as to con- 

 siderably extend the list of Cichlid tishes in which the parents protect their 



