524 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



muscle ; the young thus fed and fixed would, no doubt, 

 soon be suffocated were their respiratory tube of ex- 

 actly the same form as that of the adult ; to prevent 

 such a catastrophe the larynx is prolonged at its upper 

 end into a conical projection, which is inserted into 

 the cleft of the soft palate, and is thereby brought into 

 direct connection with the nasal air passages. By 

 these means the nutrient milk can pass with as much 

 safety into the gullet as the water does in the case of 

 the Cetacea. (See page 242.) Here we have an example 

 of how in different groups the same result is attained 

 to by the use of the same kind of means. 



Very striking differences are to be observed among 

 various Vertebrates as to their care of their young. 

 Most Fishes lay their eggs in the water, where they are 

 fertilised by the male and left to hatch ; in very rare 

 cases does the female exhibit the least care for them ; 

 indeed, but two are known ; Aspredo, after deposit- 

 ing her eggs, is known to attach them to her belly, 

 where they stay till they are hatched, and Solenostoma 

 develops a pouch, within which are projecting fila- 

 ments to which possibly the ova become attached. The 

 male more frequently exhibits care for its young, the 

 stickleback and others forming and guarding a nest in 

 which the ova are deposited ; others carry the ova in 

 their pharynx, while the pipefish (Syngnathus), and 

 the seahorse (Hippocampus) develop a subcaudal 

 pouch in which the ova are carried till they are 

 hatched. The female Surinam toad carries her young 

 on her back, and the male Alytes obstetricans cuts the 

 gelatinous cords by means of which the ova are at- 

 tached to the body of the female, and twines the eggs 

 round his legs. Pythons incubate their eggs, and 

 during the process their temperature rises about 3 P F. 

 (Forbes). Most Birds but the cuckoo and the American 

 Cow-bird (Molothrus) incubate their own eggs, and in 

 those cases where the young are unable, when hatched, 



