204 ANATOMY. 



concave in the centre, each of which has its peculiar duct. All the 

 ducts are of equal length, and unite at one and the same spot to a 

 common sperm duct. The number of glandular bodies varies : we find 

 six in Melolontha vulgaris and Oryctes nasicornis, nine in Trichius 

 fasciatus, and twelve in Tr. nobilis, on each side. This form appears 

 to be the most complete of all, whence it is peculiar to the beetles only. 



H8- 



THE EPIDYDIMIS. 



The epidydimis is likewise a glandular organ frequently formed 

 upon the type of the true testes, and opens with a peculiar either 

 narrower or wider duct into the common duct of the sexual organs. 

 We find this organ in a few beetles only: its function also is not dis- 

 tinctly known ; the few hitherto observed forms are the following. 



We observe the epidydimis most distinctly in Hydrophilus piceus 

 (PI. XXX. f. 3). They are here two long oval pointed bodies, turned 

 back about their centre, which contain within an exterior fine tense 

 skin a second glandular one, forming many rather long and regularly 

 successive little bags. Upon a first inspection, this body appears, from 

 its narrow, contiguous and parallel bags, as a convoluted vessel, and as 

 such Suckow erroneously explains it *. From this organ there 

 originates a long broad bag, with at first a narrow but suddenly 

 distending orifice, which appears to be formed like the tracheae of a 

 spiral filament, but, upon closer investigation, displays a structure 

 similar to the epidydimis. It also consists of two membranes, of 

 which the inner parenchymous mucous membrane likewise forms 

 narrow, parallel bags, which I almost consider as the actual secreting 

 cavities. In them we find a yellowish finely granulated liquid, the 

 secretion of this epidydimis. Both these bags (PI. XXX. f. 10. aa.aa.) 

 open at the end of the common duct in front of the sperm bladder. 

 (The same, a *. a*.) They are somewhat longer, or certainly quite as 

 long as the testes with the sperm duct, and extended they are of about 

 the length of the abdomen, but they are usually rolled spirally. Similar 

 appendages are found in Lytta and Meloe, but the epidydimis here is 

 a serpentine, lace-shaped vessel, which, upon the ventral side, empties 

 itself into the vesicular distended point of union of both the conical 



* In Heusing., vol. ii. p. 232. 



