602 Mr. D. Sharp and Mr. F. Muir on ilic Comjmrative 



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 Unarszis haJcewelli (fig. d2h) there is a distinct ventral 

 plate between the anus and the aedeagus, and in Cupes 

 dathratus (fig. 104-104^) 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. In 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 {Erj/x) atra there are 

 nine distinct tergites and sternites, the ninth sternite 

 bearing a pair of small papilla-like processes ; in the pupa 

 there are also nine distinct 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 liave introduced tliis term because the more correct word, 

 somatic, has already a wider meaning, as opposed to the germinal 

 tissue or plasma. 



