82 MUSEUM OF COMPARATIVE ZOOLOGY. [Feb. 



above indicated. If this should fender the identification of rocks, by 

 the aid of the fossils they contain, more difficult for those not very 

 familiar with zoology, it will on the other hand afford most instruc- 

 tive evidences of the successive changes the animal creation has un- 

 dergone upon different parts of the earth's surface at different periods, 

 and show how, in earlier ages, combinations of living beings existed 

 in certain parts of the globe quite distinct from those now occupying 

 the same localities, and yet quite similar to those existing in the 

 present time in other regions. I need only allude to the similarity of 

 some of the extinct fauna of the Jurassic period to the living fauna of 

 Australia, to make this statement clear ; and similar resemblances may 

 be traced between the extinct faunae of other periods and the living 

 fauna) of other parts of the world. As one instance, already pointed 

 out on another occasion, I may allude to the resemblance of the ex- 

 tinct fauna and flora of Oettingen with that of the temperate zone of 

 the Atlantic States of North America. 



A third kind of collections embraces everything that may illustrate 

 the mode of reproduction, and the embryonic growth of each class. 

 Here are placed together eggs and embryos in various stages of de- 

 velopment, and young animals which have not yet completed their 

 growth and assumed their specific characteristics. But these collec- 

 tions do not include the preparations intended to illustrate the organs 

 of reproduction themselves, as characteristic of the different families 

 in the adult state ; these are referred to the general, systematic collec- 

 tion. 



An objection may perhaps be made to such an arrangement of a 

 museum, as requiring a larger number of specimens than are gen- 

 erally exhibited in a systematic collection, embracing in one series the 

 whole animal kingdom. It would certainly be a great mistake to 

 neglect these multiplied modes of instruction, even were it true that 

 they entail the necessity of preserving a larger number of specimens, 

 and may lead to some waste of room. I am satisfied, however, that 

 with a proper attention in the selection of the specimens intended as 

 representatives of the genera in the systematic collection, no unneces- 

 sary repetitions need be made. I have been careful everywhere to 

 avoid the introduction of large specimens in the systematic collection, 

 in order to render them more comprehensive, and to bring, at a 



