THE LARVAL CASE OF PLATVPHYLAX. 24! 



REMOVAL OF PART, OR WHOLE, OF POSTERIOR END. 



1. Thirty-first, cut off the posterior end of a case and by the 

 following day the larva had turned in the edge ; cut again. Third, 

 had slightly turned the edge. Fourth, cut 2.5 mm. from pos- 

 terior end. Fifth, had added 5 mm. to anterior end. Eighth, 

 2.5 mm. more added. Tenth, posterior edge turned. 



2. Small piece cut from the posterior end and by following 

 day the edge had been turned and four grains of sand added at 

 this end ; case but slightly smaller than before cutting. Fol- 

 lowing day the larva was dead. 



3. Second, cut piece 4.5 mm. long from posterior end of a 

 case which was 11.5 mm. in length. Third, added 3 mm. to 

 anterior end. Fourth. I mm. more had been added. Seventh, 

 2.5 mm. more added and anterior end closed. Eighth, both 

 ends of case closed and it was glued to a leaf for pupation. 



4. Second, cut piece 3.5 mm. from posterior end of a case. 

 Third, 1.5 mm. had been added to anterior end. Fourth, o. 5 mm. 

 more added. Tenth, new part now 3 mm. in length, posterior 

 end not yet turned. 



5. Ninth, cut 4 mm. from posterior end of a case and by the 

 following day 3.5 mm. had been added to the anterior end. 

 Fourteenth, a few sand grains added to the posterior end ; case 

 closed for pupation. 



These few experiments on the posterior end show that the 

 larvae are loath to work at this end of the case and the additions 

 to the shell were made at the anterior end. As the cases are 

 normally turned in at the posterior end most injuries to this end 

 will result in the larvae ultimately reversing themselves in the 

 case to re-turn the margin. We watched the larva turn from a 

 reversed to a normal position, the whole process occupying 

 about four minutes. At first the posterior end of the body is 

 protruded from the anterior opening ; the head is then bent for- 

 ward and soon appears at the opening. Next, by a seemingly 

 very strenuous effort, the body is withdrawn into the case and 

 the larva assumes its normal position. During the process the 

 second pair of legs are thrown up into a position dorsal to the 

 thorax and pointing backward. The larva takes a short rest 

 during the reversing process. That the effort is an extremely 



