I'ahki:k: .\i;\v knci.and saiui'Imiacidae 19 
seen to extend between the [lostcrior borilir dI" the l;itt<T ;iii<l the mi- 
Icriur bordvr of the sixth st'^uient itself. This is simply thi' norniul 
condition ()l)t;iining hrtwcen an\' two succeeding' se^'inents of an 
insect's hody. The ^'cnital se;^'iiuiits \\(»uld ii«'\fi- he naturally j)ullc<l 
out to a sufiicient extent to show this relation. The condition in 
Havinia has heen brought about by either an indentation of tin' 
posterior margin or a backward prolongation of the sides of the liftli 
sternum, i)erh!ips by both. In any case paired lateral lamellae would 
appear, and the connecting membrane originally joined to the posterior 
border would either be drawn forward or backward with it and be 
attached to the inner borders of the lamellae. With nuxjifications 
this is the actual condition which exists in the genera witli which we are 
dealing, and the arcli of the sixth segment has become fused with the 
fifth sternum. Even the folds present in the connecting membrane 
are suggestive of what has taken place. Figure 32 (PI. 5) shows the 
structure of the sixth segment in a species of the genus Blaesoxipha. 
The first genital segment is more or less cylindrical. Its ventral 
surface is entirely membranous and includes the posterior part of the 
pocket for the penis. The chitinous plate that forms its dorsal and 
lateral surfaces pro])ably represents the notum. Dorsally its anterior 
margin is more indented at the center, while on each side of this 
indentation are slightly raised areas, called the 'humps' (Buckel, 
Bottcher; PI. 5, fig. 31; PI. 6, fig. 40, h.). These 'humps' are well 
defined by a curved depression in the chitin except in small specimens 
in which they are less conspicuous. In such cases they may be easily 
located by the spiracular openings which are on the lines of the de- 
pressions marking their posterior limits. They are also distinguished 
by a difTerence in color. The ground color of the segments is dull 
orange, but this only shows on the 'humps' and at the posterior lateral 
edges; the remainder of the segment is generally grayish pollinose. 
Also the 'humps' are bare and shining, while the remainder of the 
segment bears a vestiture of short hairs. 
The second genital segment (eighth abdominal; PI. 5, figs. 30, 31; 
PI. 6, figs. 37, 40, g.-i) is fully as large as the first and clothed with 
longer hairs with bristles on its upper surface, but is of different .shape. 
In profile its outline roughly resembles that of a quadrant, the outline 
of which has been somewhat flattened posteriorly. Roughly, as seen 
in profile, it may be said to have four surfaces : an anterior, connected 
by membrane with the preceding segment; a ventral, bearing the 
