ECOLOGY OF EARLY JUVENILE LIFE OF UNIONID^. 79 



Little River, near Garvin, Okla. One of these specimens, found 

 by E. C. Johnston, of our party, was attached by the byssus to 

 the shell of a large Quadrula pustulosa. An observation of this 

 kind is described by Kirtland. 1 



During the afternoon of August 30, we again investigated a 

 portion of the Kiamichi River, near Roby, Okla. Here we secured 

 fourteen specimens; ten of these I secured in about half an hour, 

 one time bringing up three specimens with a handful of gravel. 

 Here again the environment was typical, fairly swift water, 

 coarse gravel, and rocks. 



A search for young mussels was also made in Blue and Boggy 

 rivers, but failed to yield specimens with functional byssus. 

 However, a number of mussels under twelve millimeters were 

 secured, representing Quadrula pustulosa, Quadrula lachrymosa, 

 Quadrula coccinea. In the Washita River, near Davis, Okla., 

 on September 2, we secured the last of our young mussels for the 

 summer. Five specimens were found in swift water about two 

 feet deep. One of these was under three millimeters in length 

 and weighed .005 of a gram. 



In the following table I show species, locality, weight in grams, 

 length, height, and breadth in millimeters, of ten of the thirty- 

 two specimens: 



The facts noted above are closely related, not only to the 

 ecology of the juvenile mussel, but also to the ecology of the 

 adult. 



i . They indicate the conditions essential for the most successful 

 growth and early development of the Unionidae. This kind of 



^'Fragments of Natural History," J. P. Kirtland, American Journal of Science, 

 Vol. 39, 1840, pp. 166-168. 



