ARRANGEMENT OF THE ANNELIDES. 17 



all writers to blend them together, even to this day; the 

 one being the most imperfect of all the Testacea, as the 

 other is of the Annulosa. Leaving these, we arrive at 

 the annulose Annelids* and the testaceous Nudibranchia. 

 Even a naturalist, looking to the outward appearance of 

 these creatures, might readily be deceived in mistaking 

 one for the other: their bodies, generally naked, are 

 often ornamented with tufts of plumed or branched ap- 

 pendages, assuming the aspect of horns, filaments, or 

 tentacula ; they are in truth the very prototypes of each 

 other. No wonder, therefore, that the older naturalists, 

 and even Linnaeus, mixed them together, since the fact 

 of one having red and the other white blood was not in 

 those days, considered of much consequence. It is seldom 

 that analogies, so striking as these, run through all the 

 component parts of two series of animals ; for it generally 

 happens that some are much more remote or obscure than 

 others. The completeness, therefore, of this comparison 

 is an additional evidence in favour of our theory on the 

 primary types of the annulose circle. Leaving the ty- 

 pical groups for the present, we shall now take a rapid 

 glance at the three aberrant classes belonging to this 

 division of animals. 



(14.) The general characters of the ANNELIDES, or at 

 least of the animals arranged by M. Savigny in this group, 

 may be thus stated. They are soft, worm-like animals, 

 mostly aquatic *, either naked, or protected by an ex- 

 ternal shelly or agglutinated tube. The body is wrinkled 

 transversely, or composed of annular segments. Their 

 forms are very singular, and many are ornamented with 

 beautiful colours, but these fade almost immediately 

 after death. Their body being annular, brings them 

 within the circle of the Annulosa ; but their blood is 

 red; they have usually one or more hearts, and, with 

 very few exceptions, are destitute of a distinct head: 

 the sexes, moreover, are not always separate, but the 

 majority are hermaphrodites. They are without any 

 articulated members for locomotion; although some 



* Hor. Ent. 280. 



