S. A. Arendsen Hein 



233 



These rudimentary accessory spines are sometimes as an abnormality 



strongly developed. 



The following cases, differing from the normal state, occurred : 



1°. Four spines, of which one to the left, and three (joined in a 



group) to the right of the median-line (Fig. 5, No. 1)(1 individual). 



A 



6 



Fig. 5. 



2". Four spines, of which two in the normal place, the other two are 

 found on one side, somewhat below the boundary between the last seg- 

 ment, and the last but one. 



These last two spines are abnormally developed accessory spines, of 

 which mention was made above (Fig. 5, No. 2) (1 individual). 



3°. Three spines, the middle one of which lies in the median-line, 

 the other two symmetrically to the left and right of it (Fig. 5, No. 3) 

 (1 individual). 



4°. Two spines, of which one normal and one rudimentary (Fig. 5, 

 No. 4) (4 individuals). 



5°. One well developed spine, Ipng in the median-line (Fig. 5, No. 5) 

 (7 individuals). 



6°. Total absence of spines (Fig. 5, No. 6) (2 individuals). 



All those variations, which were isolated from a number of 10,000 

 larvae, are maintained again in the pupae of these larvae, as is shown by 

 Nos. 1—5 of Fig. 6. 



