THE LARVAL CASE OF PLATYPHYLAX. 239 



the new part was now 8 mm. long, or 2 mm. longer than the 

 part removed, and it was also somewhat wider. Fourth, new 

 piece 10 mm. in length. Seventh, larva had added 2 mm. more 

 and closed the shell for pupation. 



2. Fourteenth, case 1 1 mm. in length cut and both pieces left 

 on larva. Fifteenth, the larva had thrown off the posterior piece 

 and built 2.5 mm. to anterior end of piece (anterior) which it had 

 retained ; total length 7 mm. Sixteenth, length of shell had 

 been increased to 1 1 mm., the original length. 



3. Fourteenth, case 10 mm. long was cut and both pieces left 

 on the larva. Fifteenth, the posterior piece had been thrown off 

 and 3.5 mm. built on to anterior end of remaining piece. Six- 

 teenth, enough had been added to make entire length of case 10 

 mm. ; equal to the original. 



4. Second, a case I I mm. long was cut and on the following 

 day the posterior half had been thrown off and 4.5 mm. added to 

 anterior end of the piece retained by the larva. During the day 

 the larva reversed itself in the case and turned in the posterior 

 edge ; total length 9 mm. Fourth, removed the new anterior 

 part which the larva had built. Fifth, had again added 4.5 mm. 

 to old part of case. Eleventh, abandoned old shell and built a 

 new one which, by the fourteenth, was 9 mm. long. 



5. Second, a shell 9 mm. in- length was cut and by the follow- 

 ing day enough had been added to the anterior piece of the old 

 case to make it 10 mm. long. Fourth, cut between old (posterior) 

 and new (anterior) parts. Fifth, had thrown off the old (posterior) 

 piece and added 3 mm. to other part. Seventh, case had total 

 length of 9 mm. Fourteenth, total length 10 mm. 



6. Fourteenth, cut a shell 10 mm. long ; the same day the 

 larva threw off the posterior piece and added 2 mm. to the an- 

 terior end of the piece. Sixteenth, length of new part only 3 

 mm. and on the next day had increased to 3.5 mm.; total length 

 of case 9 mm. 



7. Thirty-first, case 1 1 mm. in length was cut and on the fol- 

 lowing day the posterior piece had been thrown off and 4.5 mm. 

 added to anterior end of the piece retained by the larva. Third, 

 case was cut between the new and the old parts. Fourth, old 

 part (posterior piece) had been thrown off and enough added to 



