1 1 



ioth of April the first batch hatched out, being 20 — 21 days 

 in the egg as compared with 16 — 17 for /. pahistvis. The 

 colour of the recently-hatched larva is pale purplish red ; 

 head broader than the thorax, resembling very closely 

 Nicolet's, fig. 15, plate I. (Recherches sur les Podurelles), 

 eyes distinctly on a dark patch, quite visible through the 

 shell before the egg hatches. 



The young when a day or two old are intermediate between 

 Nicolet's figure and Packard's (Embryological Studies, 

 Peabody Acad. Plate III., fig. 15). The constriction in all 

 at the commencement of the abdomen is more defined than 

 in Packard's figure, and, except that the head is not quite so 

 broad and the eyes are on an elongate dark patch, Nicolet's 

 figure represents them better. Prothorax is large, as in both 

 figures. The claws of the larval form do not differ appre- 

 ciably from those of the adult. 



The following is a series of measurements of the young 

 in comparison with a typical form : — 



Young. Adult. 



Breadth of head 7 ... 13 



mesothorax 6 ... 17 



metathorax 6^ ... 18 



1st abd. segment ... 5-J- ... 16 



widest part of abd. 6% ... 19 



,, antennae apical joint if ... 2 



Total length 24 ... 76 



Length of head 5^ ... 14 



,, prothorax £ ... nil 



,, mesothorax 3 J ... 12 



metathorax i\ ... 11 



,, abdomen 12 ... 39 



antennae 7 ... 20 



spring 6J ... 26 



It is interesting to note that, while on the average the larva 

 is about one-third the dimensions of the adult, the head in 

 the larva is broader than any other part of the body, while in 

 the adult it is only two-thirds the width of the broadest part 

 of the abdomen. Again, in the larval stage the head is 

 broader than it is long, while in the adult form it is longer 

 than broad. 



The prothorax in the young is quite distinct and easily 

 seen from above, but in the adult form it is hidden by a small 

 projection of the mesothorax (the mtsonotum of Tullberg. ) 

 The antennae in the larva are almost as broad as in the 

 adult, but" the length is only in proportion to the body. 

 This species belongs to the short-springed division of 

 Isotoma, i.e., those in which the spring does not reach the 

 ventral tube. In the young this is even more marked, for 



