CHROMOSOMES OF TIGER BEETLES 443 
The review of Harvey (’16) shows that no sex-chromosome is 
figured for a large number of species of beetles. In practically 
every instance, however, the observations were either meager or 
made by early workers. It might be concluded, therefore, that 
up to the present time the absence of the sex-chromosome has 
never been conclusively demonstrated in any species of beetles. 
3. MATERIAL AND METHODS 
The specimens used as a basis of this study were collected at 
various points in Indiana, and a record of their distribution and 
life habits is published in a separate paper (Goldsmith, 716 b). 
The most important points, however, in connection with the 
breeding habits of the tiger beetles should be mentioned, as a 
knowledge of life histories is of fundamental importance in mak- 
ing collections for cytological investigation. Shelford (08) sepa- 
rates the life-histories of the members of this family into three 
types as follows: 
(a) Eggs laid in the late spring or early summer; larvae hibernate 
usually in the third stage, pupate in the second summer; imagos emerge 
about a month after pupation, hibernate, and become sexually mature 
late in the third spring,—larval life lasts twelve to thirteen months, 
adult life ten months,—two years between generations. 
(b) Eggs laid in mid-summer; larvae hibernate usually in the third 
stage, pupate in the following June; imagos emerge in early July and 
become sexually mature very soon,—larval life ten months, adult life 
two months, one year between generations. 
(c) Eggs laid in mid-summer; larvae hibernate in the second stage, 
reach the third stage early in the second summer, hibernate again and 
pupate in the following May; imagos emerge in the early part of the 
third summer and become sexually maturesoon,—larval life twenty-one 
months,—adult life two months,—two years between generations. 
It will be noted that, from the standpoint of cytological work, 
it is practically impossible to discriminate between the form of 
type ‘b’ and type ‘c,’ as the adult life is the same, even though 
the larval life differs by eleven months. For convenience of 
discussion, therefore, I have elsewhere (Goldsmith, ’16 b) used 
the term ‘double-brooded’ to apply to all forms under type ‘b’ 
and ‘c,’ having an adult life of two months. Since the imagos of 
