Animal Morphology. 133 



muscles in relation to the muscular membrane of the 

 internal ear. 



If the sense of smell includes the nasal apparatus, down 

 to the trachea and larger bronchi, as its proper serous mem- 

 brane the mucous membrane, as extending to the same 

 parts and to the eyes, as the conjunctival membrane, and 

 to the ear, supplying, by displacement, the Eustachian tube ; 

 and the nasal and palatal muscles be viewed as the contractile 

 membrane then we have in the sense of smell a certain 

 co-ordination of structures and apparatus which, in the 

 economy of Nature, is closely interlinked with mechanism 

 and function. 



Again, as we descend in the aninual scale, we find fishes 

 merely selecting suitable localities for spawning, and the 

 male and female nidus of a new generation requires no 

 further intercourse than that the myriads of ova cast in 

 the water should, after extrusion, be fructified by the milt 

 of the male. Between these two stand an intermediate 

 group, the reptilia, which are passed by for the present, with 

 their reduced vertebras in the cervical region. 



Here, then, we have a distinct line drawn as to the order 

 of procreation, and the amount of care necessary to bestow 

 upon the young offspring. The lower the scale, the less 

 need of care for the offspring. In other words, with this 

 lowered standard of care for the young, runs the lower 

 standard of animal heat. 



If to this be added, as we lose the sense of smell, and 

 with it the accompanying sense apparatus, in the trachea 

 and larger bronchi that we have an imperfect ear, so 

 that no Eustachian tube is wanted ; and an eye of great 

 perfection, but from the medium in which it lives no 

 lachrymal apparatus is wanted then we can come to 

 quietly consider how, in such general outward conditions, 

 a bony mechanism should be withdrawn, and a distinct class of 



