10 



SMITT, ON THE UENUS LYCODES. 



By the same inanner of reasoning one will find a con- 

 stant character also in the relation between the length of 

 the tail and that of the head. At first for the ontogenetic 

 changes, in comparing the younger specimens with the older, 

 we get the following averages: 



Here we see that the figures for tbe younger specimens 

 always are lower than those for the older (juv. < sen.), and 

 that those for the Vahlii-gron-p are lower than for the reti- 

 cidatiis- gr oiv^. In auxological respect then, the former group 

 may be regarded as the more primitive. The limit between 

 the respective variations within the two groups, according 

 to o ar specimens and measurements, is to be found at the 

 figure of 41 %, so that 



^ ( < 41 characterizes the forms of the VaJilii-groji-p, 

 ""^''[>41 » » » » » reticulatus-groni^] 



althoiigh the difference is so slight, that we have found the 

 highest figure in the former group to be 40.8, while in the 

 latter group the lowest figure has been 42.3.^ In both groups 

 there is one form (gracilis, resp. frif/idus) representing the 

 juvenile characters, in such a way that its figures are the 

 lowest, although they belong to older specimens. Just the 

 same we find in the examination of the external sexual diffe- 

 rences with their evolutional changes: 



As here the males, in all the true averages, with due 

 attention to the respective ages, have higher figures than 

 the females, we have the final auxological result: 



* In a larval s])ecimen 40.9. 



