The Progress of Zoology. 249 



squirrels,, and marsupiates claim relationship with birds in their 

 faculty of flight ; the quadrumanes might as well contribute the 

 marmosets to the family of squirrels, and the Douroucouli to the 

 cats, as retain them for the doubtful character of their hands. 

 The armadillo, Dasypus a/par, is more like a turtle than a 

 mammal ; the Aard-wolf, Proteles Lalandii, is a hyena in its 

 external aspects ; the Cetacea are fishes, to all intents and 

 purposes, in then habits of life, as well as in general form. 

 Perhaps the difficulty of classing the marsupiates might be got 

 over at once by homomorphism, for as at present regarded 

 theythreaten the boundaries of Rodentia, Carnivora, Cheiroptera, 

 and Testudinata, and a classification resting on external con- 

 figuration would serve all the purpose of an index to species 

 without impeding inquiry into physiological and anatomical 

 details. As it is, the natural system affords only a few faint 

 indications of character, and the fault of all natural systems is 

 that as soon as they cease to indicate correctly they lead the stu- 

 dent astray, for after a few of the most characteristic groups have 

 been defined — as in botany the Coniferee, the Cupuliferse, and the 

 Banunculaceas, and in zoology the Quadrumana, the Carnivora, 

 and the Rodentia — there are innumerable other subjects that re- 

 fuse to conform to distinct positions by reason of their combining 

 the characteristics of many. No system can suffice to indicate 

 the place, for instance, of that curious vertebrate, Amphioxus 

 lanceolatus, which, emulating the chameleon, has a life on one 

 side, which has no necessary conformity on the other. The 

 chameleon may sleep on the left side, while the right side is 

 awake, and in the Amplvioxus the bronchial aperture, the 

 olfactory organ, and the eye, are all situated on the left side. 

 The Ghamcelonidce are, however, a well-defined group of saurians, 

 but the Brcmchiostoma is as indefinable for scientific purposes 

 as any of the cattle of fairyland. There is certainly room for 

 an artificial system of zoology of a comprehensive kind for the 

 tabulation of the entire animal kingdom. 



Looking at the several departments of zoology in their pre- 

 sent aspects, it is evident that the most satisfactory progress 

 has of late years been in the study and classification of the 

 lower forms of life. The aquarium and the microscope have given 

 an impetus to the study of the Invertebrata, and such immense 

 additions have been made to the knowledge of this great sec- 

 tion, that the mere weight of facts threatens to separate it from 

 the hitherto recognized connection with the vertebrates, and so 

 to constitute in zoology two distinct sciences, the future paths 

 of which will be separate though parallel. It is in this section 

 that we have most striking evidence of the abundance of life 

 in every region of the globe. Dr. Wallich and Mr. Gwyn 

 Jeffreys have, by their researches on the subject of deep sea 



