406 P.^REISTTAL CARE AMONG FRESH-WATER FISHES. 



One of the most singular devices for protection of the eggs is the 

 formation of bubbles of air rendered tenacious by a viscous secre- 

 tion of the mouth. This might seem to be so specialized a method 

 that there would be no indejjendent repetition by representatives of 

 a very diU'erent group. In fact, however, the method, or an analo- 

 gous one, has originated anev/ time and time again. It is manifest, 

 so far as known, in its simplest form in the fish-of-paradise {Macro- 

 podus viridi-auratus) , which makes a floating nest of a mere con- 

 glomeration of bubbles, but other species of the same family (Osphro- 

 menids) evolve nidamental receptacles little more complicated, and 

 {,mong them is the celebrated Gourami. The nests earliest described, 

 in which air bubbles formed an essential element, were those of 

 TTassars (Callichthyids of the genus Iloplofiternum)^ but in them 

 the air or " froth " was used in combination with vegetable material 

 ("" fallen leaves or grass"). The large floating nest of the African 

 Cri/mriarchus, recently described by.Budgett, may, perhaps, be partly 

 buoyed up by aeriform secretions. The future investigation of the 

 structures involved in the secretion of such bubbles will undoubtedly 

 yield most interesting results. 



More specialized than any of the methods of parental care herein- 

 before noticed is one manifested by certain American fishes. Those 

 fishes are of a family named Aspredinids, peculiar to the fresh 

 waters of South America and distantly — and very distantly — related 

 to the catfishes of the north. In them it is the female that assumes 

 charge of the eggs, and she does it in a strange and truly character- 

 istic manner. After the eggs have been discharged from the ovaries 

 (and i^resumably after they have been fertilized), the mother presses 

 her belly and breast over them and they become attached thereto; 

 then the areas of attachment of the skin become elevated into cupules 

 round the eggs, like the cups of acorns round the nuts, and not only 

 so, but strangulation ensues between each cupule and the general 

 skin of the belly, so that the eggs and cupules are borne upon stalks 

 or peduncles, and so they remain till the eggs are hatched and the 



offspring by giving them shelter in the month and pharynx. This mode of 

 nursing is illustrated " by examples of seven additional species of six genera. 

 "The natives" round the lake " say it is always the female, in the cases where 

 one of the parents takes the eggs in the mouth," that is the carrier. This 

 belief has now been confirmed by Boulenger for no less than ten African 

 genera; in fact, whenever he had been able to test the sex of the egg carrier 

 it was " invariably the female who thus carries the eggs. This was in con- 

 tradiction to statements made by Lortet and by Giinther, who ascribed the 

 habit to the male in the species of the same genus with which they had dealt." 

 Of course It is easy enough to tell by dissection w'hether a fish is a male or a 

 female, and the authors in question probably neglected to take the proper 

 means to ascertain the sex, but took it for granted that the nurse was a male. 

 See for further data the paragraphs on the Cichlids hereafter. — October 25, 

 1906. 



