174 ON ZOOLOGICAL SYSTEMS, AND THE 



differences consists in their possessing- lungs and a sanguineous system, or 

 their being destitute of lurigs and exsanguineous. 



The Linnaean method is., for the most part, built upon this general arrange- 

 ment of Mr. Ray, especially in regard to quadrupeds ; it is, however, an ex- 

 tension of it, and certainly an improvement. That of M* Cuvier, in its subor- 

 dinate division, is founded upon both these; but in its primary and leading 

 distinctions, upon the nervous or sensorial, instead of upon the respiratory 

 and sanguineous systems ; all animals, upon M. Cuvier's scheme, being pri- 

 marily divided into vertebrated and invertebrated ; those furnished with a 

 back-bone, or vertebral chain, for the purpose of enclosing the spinal marrow, 

 and those destitute of such a chain : the secondary sections, consisting of 

 vertebrated animals with warm blood, and vertebrated animals with cold 

 blood ; invertebrated animals with blood-vessels, and invertebrated animals 

 without blood-vessels. 



All these, under his last modification, which is that subjoined to his Lec- 

 tures on Comparative Anatomy,* are regarded as embracing nine distinct 

 classes ; as, I. MAMMALS ; and, II. BIRDS, which belong to the warm-blooded 

 vertebral division. III. AMPHIBIALS ; and, IV. FISHES, which belong to the cold- 

 blooded vertebral division ; and the five following, which fill up the division 

 of invertebral animals : V. MOLLUSCOUS, soft-bodied marine animals, or mostly 

 marine animals, as oysters, limpets, whelks, cuttle-fish, .pipe-worms or ship- 

 worms, defended by a testaceous covering. VI. CRUSTACEOUS ; as crabs, 

 various lobsters, shrimps, sea-spiders, and the monoculus tribes. VII. IN- 

 SECTS ; being all those ordinarily so denominated. VIII. WORMS ; embracing, 

 along with those commonly so called, leeches, and various sea-worms with 

 bristles on the sides of the body, as aphrodites, terebels or naked ship-worms, 

 serpules, amphitrites, nereids, tooth-shells. IX. ZOOPHYTES ; the term being 

 used veiy extensively, so as to include, not only all the zoophytes or plant-like 

 animals of Linna3us and other naturalists, but all their infusory, wheel, or 

 microscopic animals ; their medusas or sea-nettles, actinias or anemonies, and 

 other efflorescent worms, urchins, and star-fishes ; and thus largely infringing 

 on the molluscous order of prior arrangements. 



Many of these classes have inferior sections and subsections, under which 

 the genera that appertain to them are respectively marshalled. But in a 

 general outline it is not necessary to fo'low up the arrangement more 

 minutely. 



The common classification of zoological writers of the present day is still 

 that of Linnaeus ; and as such, it is that which I shall regularly follow up in 

 the remainder of the present study, as being best adapted to popular purposes. 

 It is probable, however, that the classification of Cuvier will ultimately take 

 the lead of it ; it is somewhat more abstruse, but considerably more definite ; 

 and offers a noble specimen of scientific ingenuity, applied to one of the 

 noblest branches of scientific study ; and I shall hence advert to this classifica- 

 tion as we proceed, for a comparison with that of the justly celebrated 

 Swedish naturalist. 



The Linnaean system of zoology divides all animals into six classes, and 

 each class into a definite number of orders ; every order consisting of an in- 

 definite number of kinds or genera; and every kind or genus of an indefinite 

 number of species : the individuals in each species being perhaps innumerable. 



The six classes are as follows : I. mammals, or suckling animals ; II. birds ; 

 III. amphibials ; IV. fishes ; V. insects ; VI. worms. 



These may be contemplated either in an ascending or a descending scale. 

 As we have begun with brute matter, and have progressively pursued it from 

 a shapeless mass to mineral crystallization, from mineral crystallization to 

 vegetable organization, and from vegetable organization to animal sponta- 

 neity, it will be most congruous still to continue in the same direction, and 

 to commence with the lowest class constituting the worm tribes. 



I. WORMS, in the Linnaean vocabulary, is a term of far more extensive 



* Lejons d'Anatomie Comparee de G, Cuvier, 8vo. 4 torn. Paris, 1805. 



