602 Mr. D. Sharp and Mr. F. Muir on the Comparative 
We cannot agree with these interpretations without proof 
from studies of the development. 
The question as to a sternite, or part of a sternite, being 
included in the male genital tube leads to the consideration 
of the number of abdominal segments, a subject beyond the 
scope of this memoir. The following points, however, bear 
upon it. In the majority of beetles the first tergite is often 
entirely membranous, and the first, second, and, sometimes, 
the third sternites are also membranous; beyond these the 
segments are distinct, and, in many cases, there appears to 
be one sternite missing. 
In Enarsus bakewelli (fig. 92b) there is a distinct ventral 
plate between the anus and the aedeagus, and in Cupes 
clathratus (fig. 104-104b) there is a pair of sub-anal 
appendages. These facts seem to indicate that there 
exists In some cases a sternite between the anus and 
aedeagus although it is only represented by membrane 
in so many forms. 
We have not been able to find the eleventh (Berlese) 
sternite in Lucanus cervus, In this species, as in a great 
number of others, the rectum is capable of being evagin- 
ated. In some cases the rectum has chitinous supports 
to facilitate this process. Jn the larvae of many of the 
Cassidae the rectum is quite telescopic, and is thrust out 
and turned up to enable the larva to fasten filaments of 
excrement to its back. If any part of the aedeagus is of 
chrootic (pertaining to the body wall*) origin it is the 
tegmen, which in that case is derived from one of the 
sternites. When a sclerite of the genital tube exterior 
to (or anterior to) the tegmen exists it may probably be 
of chrootic nature. 
The only observation as to development that we can at 
present contribute to this discussion is a slight one on a 
Cistelid. In the larva of Cistela (Eryx) atra there are 
uine distinct tergites and sternites, the ninth sternite 
bearing a pair of small papilla-like processes; in the pupa 
there are also nine distiuct tergites and sternites, and the 
ninth sternite bears the pair of papillae; in the female 
imago the genital styles are direct continuations of these 
papillae on the ninth sternite, and they lie within them at 
the end of the pupal stage. 
* We have introduced this term because the more correct word, 
somatic, has already a wider meaning, as opposed to the germinal 
tissue or plasma. 
