8 Thirty-first Report on the State Museum. 



Palaeontology, etc. The Palaeontological series, through the lower and upper 

 Silurian and Devonian formations, has been reviewed and in part re-arranged ; 

 some errors in determination have been corrected ; and fifty labels changed in 

 conformity to the present nomenclature. A few additions have been made to 

 the collections in the cases. 



On the second floor the collection of British fossils, of the Silurian, Devonian, 

 Carboniferous, Permian, Triassic, Jurassic, Cretaceous and Tertiary forma- 

 tions, have been rearranged in the table-cases ; and fossils of the same formations 

 which had occupied eighteen drawers have been incorporated with them, filling 

 the entire space ; while the remaining part of the Jurassic and Cretaceous fos- 

 sils are arranged in drawers beneath the table-cases. 



Three additional table-cases, mainly filled with arrow-heads, have been added 

 to the collection of stone implements. The entire collections of this character 

 now occupy fourteen table- cases. 



Mechanical Facilities for work in the Museum. 



The importance of a more thorough knowledge of the structure of rocks, 

 minerals and fossils than can be obtained by superficial examination, even when 

 aided by an ordinary magnifier or microscope, has long been felt in the course 

 of our Museum work. This has been found especially true in the study of the 

 fossil Sponges, the Bryozoa, in all forms of Corals, the shells of Brachiopoda, etc. 

 Even where minute or microscopic structure is not sought for, as in the Cepha- 

 lopoda and other forms, means for examining the interior structure by artificial 

 sections is of the utmost importance. 



To accomplish this work, a small turning-lathe had, during the year 1876, 

 been arranged in one of the basement working-rooms, but it required excessive 

 labor and a wasteful expenditure of human strength to accomplish even a moiety 

 of the work needed. Upon application to the Board of Regents, in 1877, I 

 was authorized to purchase and place in this working-room a small steam-engine, 

 with the necessary apparatus for cutting and polishing specimens. The whole 

 has been established, and has been working in a most satisfactory manner since 

 May last. The work accomplished has been of various kinds, including speci- 

 mens from all the classes mentioned above, but chiefly Sponges, Bryozoa, Corals 

 and Brachiopoda. These have been cut in thin sections, polished and attached 

 to glass plates, and ground down so as to be translucent or semi-transparent, and 

 are thus fitted for microscopic slides, or for a critical examination under an 

 ordinary magnifier. 



The value and importance of this work cannot be too highly estimated. With 

 our present facilities, we are able in a few hours to obtain translucent sections of 

 any fossil form, cut from the original body in different directions, and present- 

 ing the details of structure far more perfectly than could be obtained by any 

 other process. The same is also true of rock specimens and minerals, where the 

 structure is brought out in a most satisfactory manner. 



The specimens thus prepared are susceptible of being photographed, and are 

 reproduced in great exactness by the Albertype process. Some examples of this 

 mode of representing the minute structure of fossil sponges have already been 

 laid before you. Other specimens are illustrated in the volumes entitled 

 " Illustrations of Devonian Fossils," published in 1876. The absolute accuracy 

 obtained by this process renders it of the utmost value, as it precludes any 

 chance of misrepresentation. 



This process of preparation of rock specimens has been long in, use in the 

 laboratories of Europe; and in the hands of Professor Zirkel, of Leipsic, and 

 others, has contributed most important results to our knowledge of petrology. 



