223 



XTI. Notes on the Ontogeny and Morphology of the male 

 genital dike mColeoptera. By Frederick Muir, F.E.S. 



[Read June 5th, 1918] 



Plate X. 



In a former paper* I described some stages in the develop- 

 ment of the male genitalia of some species of Coleoptera. 

 Since then I have filled in a few more stages of the same 

 species, but I have not been able to extend my observations 

 to other forms. I would not consider it of any use to repeat 

 what I have said elsewhere were it not that some of the 

 leading authorities on insect morphology have failed to 

 understand the structure of the organ, and most workers 

 repeat their statements without any qualifications. Kolbe f 

 in describing the male genitalia of Rhynchophorus phoenicis 

 has mistaken the eighth abdominal segment for the aedeagus, 

 and the rectum for the ejaculatory duct. Several writers 

 have stated that the median lobe and the tegmen are com- 

 posed of amalgamated paired lobes or parameres, and 

 others have stated that certain segments, or parts of seg- 

 ments, of the abdomen are included in the structure. As 

 an extreme exponent of this latter view I may quote 

 Hopkins,t who has tried to homologise the armature on 

 the internal sac with parts of the tenth abdominal segment. 

 I can find no evidence to support these views either in 

 development or comparative morphology. 



Development. 



In the early stages of Rhabdocnemis obscura (Boisd.) the 

 testes are connected by a Y-shape thread to a median 

 point between the ninth and tenth abdominal sternites. 

 During the development of the pupa the area where the 

 thread is attached to the body wall invaginates and forms 

 the genital invagination. The bottom of this invagination 



* Psyche 22 (1015), pp. 147 152. pi. XII. 



f " Einfiihrung in die Kenntnis der Ensekten," IS!):!, p. :>22, figs. 

 225, 226, 227. 



X "On the genus Pissodes," V. S. Dep. Agric. Ent. Tech. Sir. 

 20, I, l!)l I. 



TRANS. ENT. SOC. LOND. 1918. PARTS I. II. (DEC.) 



