THE NATATORIAL FORM. 953 
potamus, or river horse, but for the extreme shortness of 
its legs, would vie in bulk with the elephant: this 
also is a natatorial type, and we find it possessed of all 
the leading characters, under new modifications: a large 
head, thick and blunt snout, short and imperfect feet, 
and aquatic habits, leave the analogy indisputable. The 
ostrich is the largest bird in existence: it is not nata- 
torial, because it belongs to a different order ; but nature 
has contrived that all the other indications of its type 
should be preserved: the bill (corresponding to the 
snout of quadrupeds) is broad, depressed, and obtuse, 
and the wings (the chief organs of motion among birds, 
as feet are among quadrupeds,) are so short as to be 
almost useless. Crabs, among annulose animals, are 
the largest and the most aquatic of all wingless insects 
(Aptera L.), for in that division were they placed by 
Linneus, and to that they truly belong: the head is 
enormous, and in many is so confounded with the thorax 
that the two parts appear but one. If we pursue the 
analogy to the winged orders (Ptilota), we find the 
gigantic Neuroptera, at the head of which stand the 
dragon-flies, living the greater part of their lives in 
water, and the genus Mantis far surpassing all other 
insects in bulk. We shall hereafter endeavour to point 
out the probable station of those stupendous fossil rep- 
tiles, the ichthyosaurus, plesiosaurus, &c., and which we 
consider as constituting the natatorial type of the 
Reptilia ; preserving, even in their fossil remains, all the 
properties of such types. Now, to prove that these 
examples are not taken at random, but are actually sup- 
ported by analysis, we shall place before the reader 
a table of the aberrant types of some of the groups we 
have here intimated : — 
Aberrant Group of the 
= 
Series of Seriesof Verte- Seriesofthe Seriesofthe Series of 
Quadrupeds. brata. Pachydermata. MRasores. the Ptilota. 
Ungulata. Reptiles. Megatherium. Guan. Hymenoptera. 
Glires. © Amphibia. Hyrax. Pigeon. Coleoptera. 
Cetacea. Fishes. Hippopotamus. Ostrich. -Neuroptera. 
