ESSAY ON CLASSIFICATION. 



Part I. 



parasites, living in the cavities or in the organs of other animals ; the Crustacea are 

 partly marine and partly Huviatile, a few are terrestrial ; the Insects are mostly ter- 

 restrial or rather aerial, yet some are marine, othei's fluviatile, and a large number of 

 those, which in their perfect state live in the air, are terrestrial or even aquatic 

 during their earlier stages of growth. Among Vertebrata ^ the Fishes are aU aquatic, 

 but partly marine and partly fluviatile ; the Reptiles are either aquatic, or amphibious 

 or terrestrial, and some of the latter are aquatic during the early part of their life ; 

 the Birds are all aerial, but some more terrestrial and others more aquatic ; finally, 

 the Mammalia though all aerial live partly in the sea, partly in fresh water, but 

 mostly upon land. A more special review might show, that this locahzation in con- 

 nection with the elements in which animals live, has a direct reference to peculiari- 

 ties of structure of such importance, that a close consideration of the habitat of ani- 

 mals within the limits of the classes, might in most cases lead to a very natural 

 classification.^ But this is true only within the limits of the classes, and even here 



8vo. fig. — Entozoorimi Synopsis, Berolini, 1819, 8vo. 

 lig. — GuKLT, (E. F.,) Verzeichniss der Thiere, bei 

 wclclieii Entozooii gefundrii worden siinl, Wiegman's 

 Archiv, 1845, contin. by Creplin in the following No. 

 ■^DujAKDiN, (Fel.,) Histoire naturelle des Hel- 

 minthes ou Vers intestinaux, Paris, 1844, 1 vol. 8vo. 

 — DiESiNG, (C. M.,) Historia Vermiuni, Yindob. 1850, 



2 vols. 8vo. That of Crustacea from Milne-Ed- 

 wards, Histoire naturelle des Crustaces, Paris, 1834, 



3 vols. 8vo. fig. — Dana, (.1. D.,) Crustacea. Uni- 

 ted States Exploring Expedition, under the command 

 of Ch. Wilkes, U. S. N., vol. xiv., Philadelphia, 1852, 

 2 vols. 4to., atlas, fol. For tlie geographical distri- 

 bution of Insects I must refer to the general works 

 on Entomology, as it would require pages to enu- 

 merate even the standard works relating to the dif- 

 ferent orders of this class ; but they are mentioned 

 in : Percheron, (Ach. R.,) Bibliographie entomo- 

 Ipgique, Paris, 1837, 2 vols. 8vo. — Agassiz, (L.,) 

 Bibliographia Zoologiie et Geologiie ; a general cata- 

 logue of all books, tracts, and memoirs on Zoology 

 and Geology, corrected, enlarged, and edited by II. 

 E. Strickland, London, 1848-54, 4 vols. 8vo. (Ray 

 Society). 



^ For the geographical distribution of Fishes, 

 consult: Cuvier, (G.,) and Yalenciennes, (A.,) 

 Histoire naturelle des Poissons, Paris, 1828-1849, 22 



vols. 8vo., fig. — Ml'LLER, (J.,) und Henle, (J.,) 

 Systematische Beschreibung der Plagiostomen, Ber- 

 lin, 1841, fol. fig. For that of Reptiles: Dumeril, 

 (A. M. C.,) et BiBRON, (G.,) Erpetologie generate, 

 ou Histoire naturelle complete des Reptiles, Paris, 

 1834-1855, 9 vols. 8vo. fig. — Tschudi, (,I. J.,) 

 Classification der Batrachier, Neuehatel, 1838, 4to. 

 Mem. Soc. Neuch. 2d. vol. — Fitzinger, (L. J.,) 

 Systema Rcptilium, Yindobonae, 1843, Bvo. For that 

 of Birds: Gray, (G. R.,) The Genera of Birds, illus- 

 trated with about 350 plates by D. W. Mitchell, Lon- 

 don, 1844-1849, 3 vols. imp. 4to. — Bonaparte, 

 (C. L.,) Conspectus generum Avium, Lugduni-Bata- 

 vorum, 1850, and seq. 8vo. For that of Mammalia: 

 Wagner, (A.,) Die geographische Yerbreitung der 

 Siiugthiere, Yerhandl. der Akad. der Wissensch. 

 in Munchen, Yol. I Y. — Pompper, (Herm.,) Die 

 Siiugthiere, Yogel und Amphibien, nach ihrer geo- 

 graphischen Yerbreitung tabellarish zusammenge- 

 stellt, Leipzig, 1841, 4to. — See, also, the annual 

 reports in Wiegman's Archiv, now edited by Tro- 

 schell ; the Catalogues of the British Museum, of 

 the Jardin des Plantes, etc. 



° Agassiz, (L.,) The Natural Relations between 

 Animals and the Elements in which they live. 

 Amer. Jour, of Sc. and Arts, 2d ser., vol. 9, 1850, 

 8vo., p. 3G9. 



