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THE AMERICAN NATURALIST [Vol.XLVI 



antennae, were clothed with a felt-like cloak of tiny eggs each a 

 little less than a millimeter long and imbedded in a small cup 

 which is affixed to the carapace. The cup has been described 

 for other species of Corixida? which attach their eggs to stems 

 of water plants and is not to be considered as a special adapta- 

 tion in the present instance. It was found, however, that the 

 carapace was slightly impressed for the reception of each egg 

 cup, as if the affixing of the egg had either softened the chitin 

 somewhat, or had taken place before the hardening subsequent 

 to ecdysis had been completed. 



In a "List of Illinois Crustacea," under Cambarus immunis. 

 Forbes (I. c.) states that: 



covered above by the eggs of a species of Corixa, probably C. alternata 

 such situations, the other being as yet undescribed. 



As the present writer has taken Ramphocorixa in Illinois it is 

 highly probable that it was the "yet undescribed" species men- 

 tioned by Forbes. The same species of water bug is also found 

 in Texas, so that it is more than likely that the distribution of 

 the insect is coincident with that of the crayfish Cambarus im- 

 munis. Forbes states also that a "careful search of the weeds 

 and other submerged objects in the ponds discovered no other 

 place of deposit of these eggs." The writer also can testify to 

 the same point. The waterbug in question is abundant where 

 found, but its distribution is not general and it is not improb- 

 able that it is conditioned by the presence of the crustacean 

 species with which it has undertaken this unusual partnership. 

 All the Corixida? are strong flyers and "swarm" at maturity, 

 so that with the general similarity of habitat which exists 

 throughout the Mississippi Valley there is no other reason why 

 Ramphocorixa should not be equally as well distributed as some 

 other species of Corixids (e. g., Arctocorisa interrupta Say) 

 found there. 



The insect when mature, measures but 5-5^ mm. in length 

 and a very large number of females must simultaneously par- 

 ticipate in the egg laying so to cover an individual crayfish. 

 No count was attempted of the eggs on any one crayfish but the 

 number must often run well up into the hundreds. 



The investiture of eggs commingled with debris certainly 



