Anatomii of the Male Genital Tuhe in Colcoptera. 603 



Our limited material did not show us the development 

 of the male parts ; but in the imago there are nine distinct 

 tergites and eight distinct sternites, the ninth sternite ap- 

 pearing to be represented by a Y-shaped sclerite (fig. 234). 

 A large amount of dechitinisation has apparently taken 

 place at the apex of the abdomen, as well as at the base, 

 and it is possible that some part of the large membranes 

 at the apex {i. e. at the base of the genital tube) may 

 represent sternites. 



We divide the genital tube into the following parts. 

 A pair of seminal ducts leading from the testes forms the 

 zygotic portion (fig. 239 a-h), and the long, single, highly 

 irregular tube, folded back and joined to the body wall, 

 forms the azygotic portion (fig. 239 h-d, 5-1). The 

 paired, or zygotic portion («—&), along with certain glands 

 opening into it, is considered to be of mesodermic origin,* 

 and the azygotic, along with certain glands, of ectodermic 

 origin. Bordas t points out that very little is known as 

 to the origin of these glands, and consequently objects to 

 the terms ectadenia and mesodenia applied to them by 

 Escherich, and calls them accessory, or annexed glands. 

 We are not concerned with them here. 



The first part of the azygotic portion of the genital tube 

 (fig. 239 h-c) consists of a long, more or less slender, tube 

 (the stenazygotic portion) ; beyond this the tube enlarges 

 and forms the eurazygotic portion ((■-(/ and 5-1). In many 

 cases this enlargement of the azygotic portion of the tube 

 takes place before it is reflected outwards to continue its 

 course to join the body wall. We call that portion of the 

 eurazygos that is usually not external {c-d), the "internal 

 sac " (" sac interne " of Jeannel). 



In all cases that we have observed the internal sac is 

 evaginated during copulation, and forms a continuation 

 of the external parts of the genital tube. In a great 

 number of forms there is no demarcation between the 

 stenazygotic and the eurazygotic portions of the tube 

 before the outward reflection above mentioned ; in such 

 cases we say that the internal sac is undifferentiated. 

 That portion of the tube that is reflected and thus forms 

 the external portion of the organ we call phallic. But we 



* On this subject see Escherich, Zeitschr. wiss. Zool. Ivii, 1893, 

 p. 620. 



t Bordas, Ann. Soc. Ent. France, Ixviii, 1899, p. 510. 



