64 THE NAUTILUS. 



Mollusca are exceedingly few and far between, I feel that my list is 

 sufficiently complete for publication at this time. 



During the present year, the heavy rises and great floods have 

 played havoc with the various species of univalves inhabiting our 

 smaller streams. In 1907 a light-colored variety of Planorbis 

 tumidus Pfr. was found in Waco Creek in countless thousands but 

 in July of the present year repeated visits to the most favorable 

 places on this stream failed to result in the finding of a single living 

 specimen. 



In April, 1908, I collected a large number of examples of Lymnaea 

 bulimoides techella Hald and Physa viexicana conoidea C & F. in a 

 small stream flowing through Lindsey's Hollow. As my time was 

 limited, I left the collecting of a still larger series until another time. 

 A month later, during the flood, all of the mollusks in the stream 

 were washed into the Brazos River. 



On the other hand, the drying- up of most of the smaller water 

 courses in the latter part of the summer is also responsible for the 

 destruction of many species. In places along Hog Creek, during 

 the dry season, I have found thousands of fresh dead shells of Physa 

 forsheyi Lea, Planorbis bicarinatus Say and Planorbis tumidus Pfr. 

 lying together in one heap. In the same place, on a bed of sand and 

 gravel, I have found half-grown living examples of Anodonta im- 

 becilis Say. The bed of this stream, in some places, is composed of 

 pebbles and small boulders to a depth of 18 or 20 inches, and when 

 the naiads are left high and dry it is impossible for them to burrow 

 down to the line of moisture. 



At Day's Lake I have found living specimens of a variety of Unio 

 ietralasmus Say that must have been out of the water for several 

 months. They were half buried in a bank of dry earth about five 

 feet above the water line. This Unio is much more tenacious of life 

 than our species of Quadrula and Lampsilis, as a very few hours in 

 the sun usually suffices to kill them. 



Thanks are due to Mr. Bryant Walker of Detroit who kindly 

 identified most of the species on the list. Also to Mr. W. B. 

 Marshall, U. S. Natl. Mus. Washington, D. C, and Dr. W. S. 

 Strode, Lewistown, 111., to whom the others were referred. 



