1890.] NATURAL SCIENCES OF PHILADELPHIA. 477 
bell, much new material, intended to illustrate the complete rnala- 
cological fauna, fossil as well as recent, of the United States, has 
been received, and the hope is held out that before very long this 
important series may be fully established. 
The department of the Academy which is to-day perhaps most 
deficient is that of Mammalogy. This department has been in a 
practically stationary condition for a number of years past; but 
latterly the generosity of the Zoological Society of Philadelphia, 
acting under the authority of its able Director, Mr. Arthur Erwin 
Brown, has permitted a number of important lacunae to be filled by 
the contribution of much important material that could be furnished 
only by an institution of its kind. Through its assistance the 
Academy has added very largely to the collections of osteology 
and comparative anatomy, which are now in a fair way to become 
leading features of the museum. 
Among the donations w T hich it has been the pleasure of the 
Academy to receive during the past year, is the highly valuable 
collection of fresh-water sponges made by one of its members, Mr. 
Edward Potts—without doubt the most comprehensive collection of 
the kind in the world. It comprises specimens of all the species 
that have heretofore been discovered or described, and is doubly 
valuable as being presented by the principal expounder in this field 
of zoological inquiry. 
The type microscopic slides (several hundred in number), prepared 
by Mr. Potts in the course of his investigations, are a part of this 
donation. 
In departments of the Academy not previously specified, the work 
done has been mainly of a general character. It is a pleasure, in 
this connection, for the Curator-in-Charge to express his obligations 
to his able assistant, Mr. J. E. Ives, who continues to render valu¬ 
able service in the general care and management of the museum. 
Specimens for study have been loaned during the year to Prof. 
W. B. Scott, of Princeton ; to Dr. G. Baur, of the Clark University, 
Worcester, and to Mr. Daniel Giraud Elliot, of New York. 
With the view of bringing the Academy into closer contact with 
its friends and patrons, and to more freely illustrate the nature of 
its work, it has been thought desirable by many to inaugurate a 
series of evening gatherings or receptions, at which the representa¬ 
tives of different professions and walks of life might meet in social 
converse. Two such receptions, under the direction of a specially- 
