CHAP. II. THE TESTACEA AND ANNULOSA. 5\ 



compare the two last groups in our table^ — namely^ the 

 Cephalopoda and the true fishes. These agree in con- 

 taining the largest individuals of their respective circles, 



— except, indeed, the fish-quadrupeds, or whales. Both 

 swim by means of their fins, which in both groups 

 represent the arms and feet of other animals : the eyes 

 of both are almost perfectly the same : the old natu- 

 ralists, indeed, who were more led by general appear- 

 ance than by anatomical peculiarities, considered the 

 cuttlefish and Loligo as true fishes. It may, therefore, 

 safely be said, that, if we are to decide which division 

 of the Testacea bears the greatest resemblance to fishes, 



— whether as regarding outward form or internal or- 

 ganisation, — no one would hesitate to name the Cepha- 

 lopoda as that group. 



(41.) In further confirmation of this arrangement, 

 we will take a slight glance at the classes of annulose 

 animals (which are to form the next volume of our 

 series), and compare them with those of the Testacea. 

 It is scarcely necessary to dwell upon the two typical 

 groups of each, — the Gasteropoda and the Ptilota, 

 which stand as the pre-eminent ; and the Aptera and 

 Dlthyra, as the suh-typical classes : when, however, 

 we proceed to the aberrant groups, we find the analogies, 

 as in all other instances, much stronger. How beauti- 

 ful, for instance, do the Annelides, or red-blooded worms, 

 put on the very aspect and form of the Nudibranchia ; 

 a naturalist, looking to the outward appearance of these 

 creatures, — their naked body, often covered with tufts 

 of plumed or ramose appendages, assuming sometimes 

 the likeness of horns, filaments, or tentacula, — would 

 even entertain a suspicion that they really belonged to 

 the same class of animals. No wonder, therefore, 

 that the older naturalists, and even Linnaeus, mixed 

 them together ; since the circumstance of one having 

 red, and the other white, blood, was not, in those days, 

 considered a matter of much importance. Now, this 

 analogy, which is perhaps one of the most striking in 

 the whole of the animal creation, is highly important 



E 2 



