1897] MICROSCOPICAL JOURNAL 191 



common of the filamentous algae, I was fortunate enough 

 to find in the Roche Abbey Lake, and subsequently to be 

 able to mount in its own water a well defined gathering 

 of Oscillaria spiralis, the curious and unexplained move- 

 ments of which (as of a headless screw turning continu- 

 ally on its end) were extremely interesting to watch. 



Several other and more common species of Oscillaria 

 and at least three species of Spirogyra and Zygnema 

 were abundant in the Lake. — The Naturalist. 



■ Some Facts About Podisus Placidus. 



By a. H. KIRKLAND, 



amherst, mass. 



During the month of May, 1896, while making field 

 observations in Maiden and Medford, Mass., upon the 

 insects known to attack the gypsy moth, Porthetria dis- 

 par, I found that many of the common predaceous bugs 

 upon emerging from hiberation greedily availed them- 

 selves of the food supply offered by the tent caterpillar 

 and destroyed large numbers of this insect. They enter- 

 ed the tents and prey upon the insects. 



When feeding, these Pentatomide insert the setse only, 

 and not the sheath, into ihe body of the caterpillar. I 

 have watched them very carefully under a hand lens 

 and my observations fully agree with those of Mr. Mar- 

 latt, as given in the Proceedings of the Entomological 

 Society of Washington, D. C, Vol. II., p. 249. I have 

 seen P. placidus extend its setas beyond the end 

 of the beak to a distance equal to the length of the 

 last rostral joint. When the setsB are inserted in a 

 strongly chitinized part, the struggles of the larva often 

 pull them from the sheath. In such cases the beak is 

 drawn through the fore tarsi in the same manner that an 

 ant cleans its antenuse, and thus the setse are forced back 

 into the sheath. I have also removed the setae of P. cv- 



