154 Illinois State Laboratory of Natural History. 



Anodonta imhecilis, Say. 



(Say, New Harmony Disseminator, 1829.) 



Young examples about an inch long were very common in 

 Wood and Willow Sloughs. The adults were not seen. 



Localities: W^illow Slough, Lily Lake, Wood Slough. 



Unio alatiis, Say. 



(Say, Nich. Enc, Am. ed., pi. iv, fig. 2, 1816, 1818, 1819.) 



Taken in Willow Slough and Lily Lake. 

 Unio gracilis, Barnes. 



(Barnes, Silliman's Jour., ii, 174, 1823.) 



Taken in Willow Slough. 

 Utiio Icevissimus, Lea. 



(Lea, Am. Phil. Soc, iii, pi. 13, fig. 23; Obs. on Genus 

 Unio, L) 



This is one of the large compressed species with angular 

 expansions of the dorsal or hinge portion of the shell. The 

 young are especially noticeable because of the large relative 

 si/e of these angular processes, and were very common in por- 

 tions of Wood and Willow Sloughs. In Lily Lake, also, they 

 were numerous, but were not seen elsewhere. 



Unio parvus, Barnes. 



(Barnes, Silliman's Jour., vi, 174, 1823.) 



Examples of this small clam 1.62 inches long were taken 

 in Harkness Slough. It was not observed outside the levee. 



INSECTA. 



Unfortunately, little has been done on aquatic insects by 

 entomologists, beyond describing and naming the species, and 

 a search through the writings of American and foreign authors 

 does not yield much of the particular kind of knowledge of 

 which practical fish work stands in need. The food habits and 

 transformations especially have been greatly neglected. AVe 

 cannot therefore give such an account of the species collected 

 as could be wished, but shall aim to add something to a knowl- 

 edge of food habits in certain cases, and to point out, as clearly 

 as we can in a brief paper, the forms whose acquaintance the 

 economic ichthyologist needs to make. 



