KEPKODUCTION AND HEEEDITY 279 



offspring after egg-laying. Such notable exception is that of 

 Aspredo lavis, a species of shad. Here the female glues the 

 egg to her body. 



The female of Solenostoma, a fish belonging to the small 

 group of the Lophobranchii, carries the egg in a bag which has 

 been specially formed by the ventral skin and fins. In other 

 Lophobranchii, however (the grotesque Hippocampus antiquorum 

 and the Syngnathus acus) in defiance of all rules it is the male 

 who becomes ' pregnant, ' for he possesses on his ventral 

 surface a roomy sac in which the eggs pass their embryonic 

 development (fig. 68). With the growing of the young brood 

 this breast-pocket enlarges enormously, and thus gives the 

 strange appearance of ' pregnancy.' Also against all rules of the 

 game, it is the female which puts on the ' nuptial dress.' 



Some other fishes which do not possess a special arrangement 

 for the care of the young carry the eggs in the mouth-cavity. 

 Thus it is reported of an inhabitant of Lake Tiberias, Chromis 

 paterfamilias, that the males at times carry up to two hundred 

 embryos in their mouth. 



The life-habits of the Brazilian frog, Pipa americana, remind 

 us of the behaviour of Aspredo which I have already mentioned. 

 In these animals both sexes share in the care of the offspring, 

 the larger and heavier share being taken by the female. The 

 male places with its anterior legs the impregnated eggs upon 

 the back of the female. The stimulus exerted by the eggs upon 

 the skin causes peculiar growths, and around these are formed 

 cells, like those of a honeycomb, in which later the young frogs 

 are found (fig. 69). 



The female of Nototrema, a frog which inhabits tropical 

 America, also carries the fertilized eggs in a pocket on her back. 

 If I further mention that the male Alytes obstetricrans winds the 

 long egg-chain round his posterior legs, and then lives for some time 

 in concealment on the land, finally to bring the young frogs back 

 into the water when they are ready to emerge, I hope to have 

 given a sufficient number of instances to show the important part 

 which is played by parental care and devotion even among the 

 lower animals. 



How closely the union becomes between the young of birds 

 and mammals and their parents requires no particular mention. 



