66 REPORT—1843. 
all instances a highly developed brain is accompanied by a corresponding degree of 
intelligence. Thus, for instance. the brain in the Cetaceans is very highly organized, 
but we should perhaps take into consideration that the brain has to be educated from 
without, and when we perceive the imperfections in the educatory media—the senses, 
in the Whales, where the organ of smell is either wanting or exists only in a very ru- 
dimentary condition; where the hands are transformed into fins, covered by a com- 
mon integument, we can conceive that the highly organized brain is given to the Whale 
to compensate for these deficiencies, and that its intelligence is not necessarily in 
degree equal to what might be inferred from the consideration of the brain abstractedly. 
The same remarks will apply to a certain degree to the brain of the Seals. The brain 
of Stenops is instanced as a case of a comparatively low brain in one of the highest 
order of Mammalia. 
As regards the Cetaceans, although the condition of the senses may be taken into 
account in considering the brain, with a view to forming an estimation of their intel- 
ligence, the author is of opinion that so highly organized a brain as is possessed by 
that group, forbids its being placed at the end of the class, as has been done. 
On the whole, the Cetacea are perhaps most conveniently located between the great 
carnivorous section and the herbivorous, as inthe table. They may be connected with 
the Pachydermata through the Lamantins, and with the Carnivora through the Seals. 
The author follows De Blainville, Owen, and some other naturalists, in separating the 
Phytophagous genera, Manatus, Halicore and Rytina, from the true Whales, with 
which they are associated by Cuvier. The animals constituting these three genera 
he regards as aquatic Pachydermata, bearing the same relations to the ordinary Pachy- 
derms as do the Seals to the Carnivora. 
In the circles representing the orders are introduced those genera, belonging to 
each, which appear to approach most nearly to other orders. Most of these approaches 
of genera of one order to the general characters of other orders have been before 
pointed out ; he does not, however, see good reasons for the belief (expressed by 
some) that the groups pass imperceptibly into each other; were that the case, there 
would be many species so well balanced in their characters that they could not, ina 
classification, without doing violence to those characters, be placed in any particular 
order ; they would require to be arranged between the orders the characters of which 
they combined. Species which even appear to require to be so located are, however, 
at least far from numerous, and in proportion as the knowledge of the groups and 
species increases, so does the number of supposed links decrease ; it becomes less and 
less doubtful in which group an animal should be placed. Instances illustrative of 
this point are mentioned. The questicn is (the author observes), whether any species 
is framed essentially on two types of the same rank? Each animal is framed to per- 
form certain functions, and is perfectly adapted to those functions, but beyond this, is 
not each species framed upon some general and particular model? Certainly it may 
be said with respect to the Water-rat (Arvicola amphibia), that it is framed on the Ver- 
tebrate model ; on the Mammalian type of that model; on the Rodent type of the 
Mammalia; and it is equally clear to the senses that it possesses the same general 
structure of skull, combined with the anchylosed fibula to the tibia, &c., which cha- 
racterize the murine family of the Rodent order. Beyond this, again, it exhibits a mo- — 
dification in the structure of the teeth, in which it agrees with numerous other species 
of the family mentioned, and which are classed under the generic title Arvicola. So 
that, in one sense, the Water-rat may be said to be essentially framed upon more than 
one model, but from the lowest to the highest of the divisions mentioned, each model 
is a modification of the type of the division which precedes it, and the case might be 
therefore symbolically represented by concentric circles of different sizes, the largest 
of which would typify the Vertebrata, and the smallest the genus Arvicola, It does 
not appear thatthe Water-rat is framed upon two or more types of equal rank, and the 
author strongly inclines to the belief that what is true of one species, as regards the 4 
point under consideration, is true of all. hd 
He next calls attention to another point connected with the genera introduced in the — 
table, observing, that it often happens that those species of one order which approach — 
most nearly to other adjoining orders, are not met, as it were, by a corresponding ap-— 
proach in those adjoining orders. Each order may throw out rays (to speak figura- 
tively) to other orders, but the rays are seldom in the same direction. Among the 
Carnivora, the genus Mydaus, in general appearance, and in its insectivorous diet, re- 
sembles the species of the order Insectivora, but it differs widely in dentition, having 

