EEPORT OF NATIONAL MUSEUM, 1919. 103 



pre-war condition. Hence the cases were, for the most part, simply 

 shifted back to their original positions, without attempting any 

 serious rearrangement, the accumulation of dust removed, and dis- 

 placed specimens readjusted. This work is not yet fully completed. 

 The collection of gems, as noted elsewhere, it was decided to entirely 

 rearrange and catalogue, a work which is still in progress. In the 

 paleontological halls only, have important changes been made, to con- 

 form to the " open aisle " arrangement of the other divisions of the de- 

 partment. The general appearance of these halls is much improved as 

 a result. Under the present arrangement the exhibits are better sys- 

 tematized and of greater value from an educational standpoint. In 

 the hall of invertebrate paleontology an educational series showing 

 the characteristic fossils and rocks of each geological period occupies 

 the north side; a line of low-standing exhibits, illustrating strati- 

 graphic paleontology, extends through the center, while a series of 

 high cases along the south side contains the characteristic fossils of 

 each group of the animal kingdom arranged in biological order. In 

 this hall, therefore, three distinct aspects of paleontology are pre- 

 sented, and the arrangement of the cases is such that now, as in the 

 other halls, the visitor, by merely passing through the center aisle, 

 can gain at a glance an idea of its entire contents. 



All of the large vertebrate exhibits have been thoroughly cleaned 

 and renovated, faded labels replaced, and cases cleaned and in some 

 instances rearranged. 



The newly completed free mount of the skeleton of Diraeirodon 

 gigas has been installed, and, being beyond question the most perfect 

 skeleton of its kind anywhere displayed and the only one thus ar- 

 ticulated, it forms a striking addition to the exhibits (see pi. 3). 



A similar arrangement to that in the hall of invertebrate paleon- 

 tology has been made of the cases in the paleobotanical hall, where a 

 broad, uninterrupted aisle throughout the entire length affords the 

 open aspect. Exhibits of fossil plants of general interest are now 

 placed along the south wall, while standard upright cases along the 

 north side contain the stratigraphic series. 



The closing of the exhibition halls during the greater part of the 

 year afforded an unusual opportunity for work on the study and 

 duplicate collections and for research. This was taken advantage 

 of in all divisions of the department. In the division of systematic 

 and applied geology much time was devoted to the preparation of 

 100 sets of 21 specimens each, illustrating the secular decay of rocks 

 and intended primarily for distribution to agricultural schools. - The 

 work of preparing 100 sets of ores and minerals has made considerable 

 progress, but as this must be done at odd moments and no special 

 funds can be applied to it, progress is necessarily slow. Over one- ' 



