34 



COMPARATIVE ZO-OLOGY. [June, 



species need to be brought to light, thus furnishing the most 

 abundant means for the study at once of the permanency, and 

 of the variability of organic characters. With the same end 

 in view, it is the purpose to select specimens of both sexes, 

 and of various stages of growth, that the whole truth may be 

 known according to the facts of nature. 



4. The Chronologic Collection. This is intended to com- 

 prise a single example of every distinct species found on each 

 geologic horizon without regard to locality. It is thus suited 

 to indicate as well the life-period of each species, genus and 

 family, as the orderly succession of these groups in time. 



5. The Students' Collection. This collection, equally with 

 each of the other collections, has its distinctive aim. The 

 end kept prominently in view in its formation is twofold, 

 viz., to meet the wants of the teacher in furnishing suitable 

 means for illustration, and the necessities of the pupil in sup- 

 plying appropriate material for study. 



It is scarcely necessary to add that, in the formation of 

 these collections, specimens for sections illustrative of the 

 internal structure of given organic forms, are in constant 

 process of selection, while all the material which remains 

 unused is set aside, after being duly labelled, for exchange. 



In closing this report, reference might be fitly made to the 

 additions to this department of the Museum during the year. 

 The palseontological collections have, however, been so greatly 

 enlarged by the reception of specimens from other institutions, 

 that a mere enumeration of them would unduly swell this 

 report, and is therefore omitted. 



Report by Dr. G. A. Maack. 



The progress I have made since the writing of my last 

 report concerns the osteological collection of the Museum. 

 The examination and arrangement of this collection have at 

 present advanced so far that I am able to report it as very 

 complete in many points, while its general character stands 

 in proper proportion to all the other collections of the Museum. 

 As this collection had never been arranged when I took charge 

 of it, but was packed up in a large number of boxes, which 



