4 Journal New York Entomological Society. [Voi. xxv. 



its tip (Plate II, figs. 2 and 5). These stylets are roundly notched 

 on their outer side, as shown in the drawing and the opening is 

 capable of some enlargement — facts which enable us to understand 

 how some surprising bits of material come to be found in the diges- 

 tive tract. (We have found oscillatoria 9/10 mm. long and bits of 

 Zygnema filaments consisting of as many as seven cells.) 



We have spent many delightful hours watching the boatmen in 

 their natural surroundings and in the aquarium and feel safe in say- 

 ing that the customary food of Corixids consist of such matter as is 

 to be found in the brownish deposits on the bottom of the pool and 

 upon the dead leaves that have lodged in its shallow waters. These 

 deposits consist of tiny bits of organic matter, diatoms, desmids, 

 oscillatoria, sometimes threads of live, more often dead filaments of 

 Zygnema, Euglense, Paramecium, Chlamydomonas, spores of various 

 algae and the cysts of Euglense and other unicellular plants and animals. 



That these things form the daily fare of Corixids can be sub- 

 stantiated by any one who cares to examine the stomach contents of 

 a few of them.^ To be able to say just what, out of all the matter 

 they take into their little bodies, nourishes them, is a more difficult 

 matter, and involves feeding them on pure cultures. But for the 

 purposes of this paper, it is enough to point out the source and nature 

 of their food supply and call attention to the fact that here may be 

 one reason for their dominance. 



Annotated Bibliography. 



1. Abbott, James Francis. A New Type of Corixidse {Ramphocorixa bala- 



nodis n. gen. et sp.), with an Account of Its Life History. Can. Ent. 

 1912 : p. 113. 



2. Geise, Otto. Die Mundtheile der Rhynchoten nach Untersuchungen an 



einigen- Wasserwanzen. Bonn, Universitats Buchdruckerei von Carl 

 Georgi. 1883. 



3. Hagemann, Johannes. Beitrage zur Kenntnis von Corixa. Zoologische 



Jahrbiicher, Anatomie 30, 1910. 



4. KiRKALDY, G. W. A Guide to the Study of British Waterbugs (Aquatic 



Rhynchota). Entomologist, 1899, p. 6. 

 1 The reader might be interested to know that I have reared Corixids 

 from e^g to maturity in 1 1 cm. petrie dishes. As many as twelve have been 

 reared in one petrie by giving them a few pipettes full of fresh sediment each 

 day. In a few instances in the past have appeared accounts of Corixids feed- 

 ing on animal organisms. After having watched them repeatedly strike out 

 of their way, during their foraging, ostracods and similar organisms I am con- 

 vinced the observations are exceptional or misinterpreted. 



