ArticLe I]1—On the Distribution of the Fresh-Water Sponges 
of North America.* By FRANK SMITH. 
In the preparation of this paper there have been two purposes in 
mind. One of these is the presentation of the results of studies thus far 
made on the fresh-water sponges of Illinois; and the other is to assemble 
_ in more convenient form the information which we now have concerning 
the distribution of such sponges in North America. Preliminary to the 
more detailed presentation of data it is desirable to give a brief sum- 
mary of our knowledge of the fresh-water sponges of this continent. 
HIsTORICAL 
The greater part of what is known on the subject at the present time 
is the result of the work of less than a half dozen men, and was gained 
during the decade 1880—1890. The most important work is that of Dr. 
Edward Potts, of Philadelphia, who contributed something over twenty 
short papers on the subject, besides his monograph—which appeared in 
1887. Most of his papers appeared in the Proceedings of the Philadelphia 
Academy of Sciences. His collecting was done chiefly in Pennsylvania 
and New Jersey, in the vicinity of Philadelphia. An active co-worker with 
Potts was Henry Mills, of Buffalo, N. Y., who collected in his own state 
and occasionally in Florida, lowa, and northern Illinois. About a dozen 
brief papers and a few new species appear to his credit. His publica- 
tions were chiefly in various journals of microscopy which abounded in 
the decade just mentioned. A. H. McKay, principal of an academy in 
Halifax, N. S., was an active collector in Nova Scotia and Newfoundland, 
and contributed a half dozen papers and a few species of uncertain status. 
B. W. Thomas, of Chicago, a devotee to microscopy, did a good deal of 
collecting in northern Illinois for other workers, but not much writing. 
This quartet of workers was in close relation with H. J. Carter, of Eng- 
land, who was one of the leading specialists in the whole group of 
sponges, and they with certain Canadian collectors supplied Carter with 
material which served as a basis for a few papers on American forms and 
for one new species. 
Of the approximately thirty known species of North American fresh- 
water sponges, about twenty were described during this decade, chiefly by 
Potts, and but one of them by a European. Some ten or eleven species 
were found in each of the states of Pennsylvania, New Jersey, and New 
* Contributions from the Zoological Laboratory of the University of Illinois No. 174. 
