460 STATUS OF ARISTOTLE IN SYSTEMATIC ZOOLOGY. 
that animals are viviparous, oviparous and vermiparous. Such 
a distribution would naturally occur to one who had observed a 
number of facts, but very little scientific knowledge would suffice 
to correct the erroneous first impression. 
Further, among the viviparous animals are included man, the 
horse, the seal,* and others with hair; and among marine animals 
the cetaceans, but so are also the Selachians (I, iv, 1) and, in 
another chapter (I, vi, 2), the viper is added. He makes, it is true, 
a distinction between such as are internally viviparous and ovipa- 
rous (I, iv, 2) for he had not conceived of the possibility of the 
truth embodied in the aphorism ‘‘omne vivum ex ovo” but there is 
no evidence that he had any conception of the significance of the 
character observed, or that if called upon to subordinate the 
groups of animals, he would have classed them otherwise than 
ordinary observers of the same facts would have done and, in 
numerous cases and with knowledge of the same facts, did after- 
wards: it is at least, an assumption which is even negatived by 
other observations of Aristotle, and rendered improbable by eis 
knowledge of the operations of the mind exhibited by others m 
the classification of facts. 
If, on the one hand, Aristotle appears to recognize, in the state- 
ment that the Selache are viviparous fishes (VI, x, 1), that the 
Cetaceans are not fishes, but a peculiar group (I, vi, 1) like birds 
and fishes; on the other hand, by direct association of them with 
Selachians as viviparous aquatic animals (VI, xi, 4) and their 
contradistinction from viviparous animals with feet and from man, 
as well as from the oviparous fishes, he removes them to 4 still 
greater extent from the ordinary mammals + and raises a doubt what 
really were his ideas as to their relations. 
2. RECOGNITION OF HOMoLOGIEs.—Although recognizing homolo- 
gies in a vague manner (I, i, 3, 4), as any one capable of thinking 
and expressing his thoughts must do to a greater or less extent, 
his appreciation rarely advanced much if at all beyond the popular 
views, and hes frequently confounded the relations of true homol- 
ogy and analogy, putting, e. g., in the same category, the relation 
of the nails and hoofs of ordinary quadrupeds and the nails of the — 
sk pancreas ea 
Ls s is PS i yi. 
* The seal, in th pl faot tas 3 P ae ginous b > i (Ce 
3), was associated with the cetaceans, as were also the sawfish (Pristis) and Bovs ™ 
atoptera?) (VI, xi, 1.) : 
