374 Illinois State Laboratory of Natural History. 



and tine filamentous alg;e. They would grasp the threads of 

 alga? with the rami and chew them preparatory to swallowing. 



56. E. dilatata Ehrbg. 



This species was present from July to September in the 

 river and deeper lakes, being found at the same substations 

 as the foregoing species and reaching its greatest abundance 

 in July. It was the only member of its genus found in Dog- 

 fish Lake, where it continued to occur until December, long 

 after it had disappeared at the other substations. It was 

 also found once in April in this lake. 



57. E. triquetra Ehrbg. 



Not so abundant as the preceding species ; found only in 

 the Illinois River and Quiver Lake, from June to October. 

 This is the most conspicuous and beautiful representative of 

 this genus. It may very readily be distinguished by the 

 curious "three-winged" shape of the lorica. 



58. E. deflexa Gosse. 



This was found only in towings from Quiver Lake during 

 the period from May to September. 



59. E. pyriformis Gosse. 



Of infrequent occurrence, during November, in towings 

 from Flag Lake. 



Family CATHYPNID^. 



CATHYPNA Gosse. 



Lorica subcircular horizontally, usually much arched verti- 

 cally ; lateral inangulation wide and deep ; toes two, furcate. 



60. C. luna Ehrbg. 



This species was present from April to December, and at 

 all of the substations except B. Its maximum of abundance 

 was reached in July and August. The records for the first 

 and second year are very similar. 



61. C. leontina Turner ('92). 



Seasonal distribution about the same as that of C. luna. 

 It was found in the Illinois River and deeper lakes, and was 

 present both in towings and among vegetation. It was com- 

 monest about July. 



