24 THE AMERICAN MONTHLY [Jan., 



inaccessible waste places where little liable to be dis- 

 turbed, its rapid growth, conspicuous massing of great 

 numbers of minute flowers, and sudden production of 

 immense numbers of hard and durable fruits well 

 adapted to a wide dissemination, and sure to germinate 

 in its damp haunts, and its protection, as we have found 

 from various enemies, — all have contributed to its em- 

 inent success in life. 



The Rhizocarps. 



By ARTHUR M. EDWARDS, M. D. 



NEWARK, N. J. 



Having lately received some slides and material which 

 contained Hhizocarps from B. W. Thomas, of Chicago, 

 111., and some papers on them from him and Sir J. W. 

 Dawson, of Montreal, Canada, I thought that a knowl- 

 edge of these microscopic atomies would be of interest. 

 They are not generally known and they do not require 

 very high power of illumination and obliquity of light 

 to see them. 



At the regular monthly meeting of the Chicago Acad- 

 emy of Science held Tuesday evening, January 15, 1884, 

 a committee consisting of H. A. Johnson and B. W. 

 Thomas submitted their report on the microscopic or- 

 ganisms in the boulder clay of Chicago and vicinity. 

 They stated that while the lake tunnel for the purpose 

 of supplying the city of Chicago with water from Lake 

 Michigan, was in process of construction, specimens of 

 the clay through which the excavation was made was sub- 

 jected to microscopical examination (Fig. 1.) The results 

 showed a disc, varying from 1-55 to 1-250 of an inch is 

 diameter. They were dark brownish-yellow in color, and 

 and apparently flat or concavo-concave, and were un- 

 known to any paleontologist to whom they were sub- 

 mitted. Slides were sent to New York and Londom 

 without result. 



