238 WM. S. MARSHALL AND C. T. VORHIES. 



4. Dorsal notch cut in case and it was completely filled the 

 following day ; this was repeated seven more times and each 

 time the notch was filled in twenty-four hours ; the ninth time the 

 repair took two days. The larvae now added a narrow band to 

 the anterior edge of the case ; this was removed and rebuilt three 

 times in as many days. 



5. Dorsal notch cut and repaired seven times daily with one 

 exception, in which the period of repair extended for two days. 



6. Ventral notch cut six times and repaired five times, each at 

 end of twenty-four hours, and once after interval of two days. 



7. Two cases, in each of which a dorsal notch was cut, were 

 repaired by the following day. 



8. Dorsal notch cut but not repaired for three days. 



9. Lateral notch cut and repaired in three days. 



10. Two cases notched, one dorsal and one ventral, were both 

 repaired in twenty-four hours, but in each instance a small open- 

 ing was left at apex of notch which was never repaired. 



Any portion of the case which has been removed from the 

 anterior part, provided the piece removed includes part of the 

 margin, was repaired in a short time. If the piece removed was 

 taken from the shell at some place away from the margin, repair 

 is neglected and the opening allowed to remain. In two of the 

 experiments recorded it will be noted that in filling in the notch 

 a small part was left open and this was never repaired. Some 

 larvae not recorded had holes cut in their shells and after a lapse 

 of several days the openings were still unrepaired. A larva can 

 easily fill in a notch 2x3 mm. in twenty-four hours. 



CASE CUT TRANSVERSELY INTO Two PIECES. 



In the following experiments the cases were cut transversely 

 into two pieces, which were as nearly equal as we could make 

 them without an actual measurement. The larvae were then 

 replaced in the aquaria with both pieces of the case still on their 

 bodies. 



I. On the first of the month a case was cut and one piece, 6 

 mm. in length removed. Second, at 8 a. m., the new part added 

 to old piece left on the larva was nearly equal to the part 

 removed, and at 4:30 p. m. it was of the same length. Third, 



