“SYSTEMATIC ZOOLOGY—GILL. 463 
the ruminants,? both groups have long been associated in the same 
order under the name Paridigitates or Artiodactyles, contrasting with 
another (comprising the tapirs, rhinocerotids and horses) called 
Imparidigitates or Perissodactyles.? 
I need searcely add that the law of correlation apphed by Cuvier 
‘to the structures of ruminants entirely fails in the case of many ex- 
tinct mammals discovered since Cuvier’s days. Zadig would have 
been completely nonplussed if he could have seen the imprint of an 
Agriocheerid, a Uintatheriid, a Menodontid, or a Chalicotherid. 
The value of this law was long insisted upon by many. Some of 
the best anatomists, as Blainville, protested against its universality, 
but one who ranked with Cuvier in skill and knowledge of anatomy, 
Richard Owen, long upheld Cuvier’s view. “ You may be aware,” 
he wrote in 1843, “that M. De Blainville contends that the ground— 
viz, a single bone or articular facet of a bone—on which Cuvier 
deemed it possible to reconstruct the entire animal, is inadequate to 
that end. In this opinion I do not coincide.”° The many mistakes 
Owen made in attempting to apply the principle proves how well 
Blainville’s contrary opinion was justified. 
The numberless remains of past animals, exhumed from the many 
formations which the animals themselves distinguished, have entailed 
constant revisions of systems resulting from clearer comprehension 
of the development of the animal kingdom. Such revision, too, 
must continue for many generations yet to come. 
CUVIER AND ANATOMY. 
The failure to sufficiently apply anatomy to systematic zoology 
was especially exemplified in the treatment of the fishes which ab- 
sorbed so much of Cuvier’s attention in later years. He, as well as 
his associate, gave accounts of the visceral anatomy and was led— 
often misled—to conclusions respecting relations by his dissections, 
@The only essential difference between the feet of hogs and ordinary rumi- 
nants is of degree in the development of the lateral hooflets. There is every 
gradation among the Artiodactyles, recent and extinct, between forms having 
the lateral hoofs aborted and those with all developed and accumbent on the 
ground, as in the Hippopotamus. 
6 Huxley had previously, in 1856, in an article ‘On the method of Palzon- 
tology” (Annals and Magazine of Natural History, 2d series, vol. 18, p. 49), 
called attention to the oversight of Cuvier; he quoted, in French, the passage 
here rendered in English, and added: “I confess that, considering the Pig has 
a cloven foot, and does not ruminate, the last assertion appears to me to be a 
little strong. But my object is not to criticise Cuvier,” ete. Apparently he 
had forgotten the facts, however, when he wrote the Introduction referred to. 
¢ Owen, Amer, Journ. Sci, and Arts, XLV, 18438, 185. 
