Cope.) 250 [Dec. 15, 
the Carnivora. The latter show their teeth and often crouch preparatory 
to a leap. 
These cases present so constant an association between habit and use, 
that admitting evolution, we are compelled to believe that the structure 
has given rise to the habit or the habit to the structure. In the former 
case, we have to suppose, with the author of natural selection, that among 
the many spontaneous variations, rudimental horns oceasionaily appeared, 
and that their possessors being thus favored in the struggle for existence, 
were preserved and multiplied; while those not favored, dwindled and 
were ultimately nearly all extirpated or starved. The question of origin 
is here left to chance, and Alfred Bennetthas made a mathematical estimate 
of the chances of any particular profitable variation occurring among the 
great number of possibilities of the case. This has shown the chance to 
be so excessively small as to amount in most cases to a great improbability. 
If we turn to the probabilities of such structure having arisen through 
the selection of that mode of defence by the animal, we find them greatly 
increased. The position occupied by the horns, in all the animals de- 
scribed, is that which is at once brought into contact with an enemy in 
conflict, and as sport among animals is a gentle imitation of conflict, the 
part would be constantly excited in sport as well. With an excess of 
growth nutrition, our knowledge of the effects of friction on the epider- 
mis, and of excessive ligamentous strain and inflammation on bone 
" (e. g., spavin in horses) as well as of abnormal exostoses in general, would 
warrant us in the belief that the use of the angles of the parts in ques- 
tion in these animals, would result in a normal exostosis, of a simple 
kind in the frogs, or as horn cores in the Ruminantia, As to the sheath- 
ing of the cores in the Bovidw, and nakedness in the Cervide, itis in 
curious relation to their habitat and to their habits. The epidermis and 
derm would of course share in the effects of friction. In the Bovide 
which dwell in treeless plains, or feed on the grasses in great part, the de- 
velopment of these coverings of the horn cores into a horny sheath, 
would naturally meet with no interruption. In the case of the deer, 
which mostly live in forests or browse on trees, constant contact with the 
latter would prevent the healthy growth of the dermal covering, and it 
would be liable to injury or constant excoriation by the animals them- 
selves on the branches of trees, etc. This we kuow to be the present 
habit of the deer as regards the dermal covering of the horns. I have 
elsewhere pointed out the similar connection between the dental structure 
and habitat among the oxen and the deer. The former eating the harder 
grasses, are provided against the consequent rapid attrition of the tooth, 
by a prismatic form, which allows of more prolonged growth and more 
rapid protrusion. The deer, in accordance with their foliage-eating 
habits, do not wear thé crown of the tooth with such rapidity. Long 
continued protrusion is not so necessary, hence the teeth are more dis- 
tinctly rooted and have a prominence or shoulder, distinguishing the 
body of the crown. 
