240 Field Museum of Natural History — Reports, Vol. III. 



lodocus. The exhibits of the Hall are for the most part, therefore, 

 illustrative of dinosaurs. The collection illustrating modes of petri- 

 faction and comparisons of living and extinct forms has also been 

 installed in this hall. It occupies three wall cases. The transference 

 of the dinosaur and other material gave opportunity for rearrange- 

 ment of the paleontologic collections as a whole, which was improved. 

 Three new wall cases were added to Hall 33 and the collection there 

 completely rearranged. About one hundred large specimens of cys- 

 toids, crinoids, trilobites, etc., were added to the Silurian series on ex- 

 hibition, and about two hundred specimens of corals, brachiopods, 

 palecypods, etc., to the Devonian. To the Carboniferous series about 

 three hundred and fifteen specimens of crinoids mounted on tablets 

 were added, filling one floor case. This material was obtained for the 

 most part from the collection purchased from Mr. Fultz. The Triassic 

 fossils were also moved from Hall 36 to Hall 33 and installed. By 

 this rearrangement it was made possible to devote Hall 36 almost 

 wholly to Jurassic fossils. Two cases of Jurassic plants and inverte- 

 brates were reinstalled in this hall and two cases of Jurassic ichthyo- 

 saurs and one of Jurassic fishes transferred from Hall 59 to Hall 36. 

 The Cretaceous collections were moved to the east end of Hall 59 and 

 new Tertiary vertebrates and invertebrates thus afforded room in 

 their proper sequence. Among new specimens of Tertiary vertebrates 

 installed in Hall 59 may be mentioned two large nodules from the Loup 

 Fork of Wyoming showing remains of the fossil horse Hypohippus in 

 the matrix, and several skulls of recently purchased Patagonian fossils. 

 Two of the two-foot wall cases in Hall 61 were replaced by three-foot 

 cases and in them were installed the series of Titanotheres and some 

 other large skulls. Some rearrangements were also made of the floor 

 exhibits in Halls 59, 60, and 61. In Hall 63 devices have been pro- 

 vided to permit exhibition of minerals that would fade on exposure 

 to light. These, although they include some of the most showy and 

 interesting specimens, had hitherto been necessarily kept in drawers 

 away from public observation. The device provided for each spec- 

 imen consists of a box of black cardboard, which is hinged and 

 placed over the specimen so as to entirely exclude the light except 

 when it is desired to examine it. A series of levers connected with a 

 button placed on the outside of the case permits raising of the box by 

 pressing the button. On releasing the button the box drops back 

 into place and covers the specimen again. The specimens are thus 

 protected from light except for the moment when the visitor wishes 



