A DIFFICULTY FOR DARWINISTS. 
319 
of classification into a sort of genealogical tree ; and yet some 
possess organs both homologically and analogically alike, that is, 
constructed in the same manner, in the same place in the body, and 
having the same functions, which cannot be hereditarily connected 
with each other. St. George Mivart's work on the " Genesis of 
Species" gives many examples of this. Improbability of similar 
complicated organisms being evolved separately on Mr. Darwin's 
hypothesis ; as well might we expect two distinct and completely 
isolated nations to evolve the same language without any com- 
munication. Illustration taken from the affinities of the teeth 
between the Marsupial rodents and carnivora, and the Placental 
rodents and carnivora. Argument strengthened by reference to a 
quadrumanous rodent, the Aye-aye. 
MARSUPIAL RODENTS 
have two upper and lower incisors, 
with persistent pulps growing con- 
tinually on the arc of a circle. The 
front, guarded by a thick plate of 
enamel, allows the softer ivory and 
bone substance of the body of the 
teeth to wear faster, and thus preserve 
a sharp edge. 
HAVE NO CANINES. 
Molars separated from incisors by 
a considerable interval. 
PLACENTAL RODENTS. 
"With the exception of the hare 
and rabbit, which have four upper 
incisors, the same description exactly 
applies to this order as to the Mar- 
supial rodent. 
HAVE NO CANINES. 
The same. 
MARSUPIAL CARNIVORA, 
e.g., THYL ACINUS. 
Eight upper incisors and six lower 
ones, small and insignificant in func- 
tion. 
Two large canines above and be- 
low, of which the lower bites in 
front of the upper. 
Six pre-molars above and below, 
formed like a spear-head, to aid in 
holding a prey. 
Eight molars above and below, 
formed for cutting up flesh and 
breaking bones. 
PLACENTAL CARNIVORA, 
DOG. 
Six upper and six lower incisors, 
small and insignificant in function. 
The same. 
Eight pre-molars above and below, 
formed like a spear-head, to aid in 
holding a prey, the last pre-molar 
formed for cutting llesh, or breaking 
bones. 
Four molars above and six below, 
the first pair of lower ones being 
formed for cutting flesh and break- 
ing bones, all the rest for gTinding. 
The dental apparatus of the Aye-aye, a quadrumanous animal 
similar to the rodent type. 
Teeth a very high type of specialised organ ; their evolution 
from bone in the sub-kingdom vertebrata traced. Conclusion. 
