13 
SYSTEM OF NATURE. 
placental fishes : the subnormal and abnormal groups ap¬ 
pear to alternate with each other in this manner,—Ferae, 
Cheiroptera, Glires, Bruta, Belluae, Cete, and the relative 
mutual similarities of the seven groups maybe shown thus:— 
Cheiroptera. 
Fer^e. Glires. 
Primates. 
Cete. Bellile. Bruta. 
The more decided structural similarities existing among 
the animals composing these seven groups are to be sought 
between the Primates, Ferae, Glires and Belluae, the ab¬ 
normal groups of Cheiroptera, Bruta and Cete, being re¬ 
garded as links connecting the placental with implacental 
or oviparous groups, rather than groups essential to the 
integrity of the placentals. I will therefore endeavour to 
point out on what grounds I have imagined a connexion 
between the normal and the subnormal placentals. 
Beginning with the Ferae, (in which group I need 
scarcely say that I include the Sorecidae or Insectivora of 
authors), we shall find these and the monkeys manifestly 
approach each other in many points, more especially in 
the teeth, shape of the head, and intellectual capacity. 
Passing to the lemurs, we come to the Cheiromys 
psylodactylus or Aye-Aye of Madagascar. Should this 
strange animal, combining as it does the dentition of the 
Glires with the opposable thumb peculiar to the mon¬ 
keys, be hereafter proved to belong to the Glires instead 
of the Primates, as many authors, including Cuvier, have 
