Page:Jardine Naturalist's library Entomology.djvu/197

Rh canal a considerable way beyond the extremity of the body. In the male the principal internal generative organs are the testes, vasa deferentia, vesicula seminalis, and ductus ejaculatorius: the external are the penis, and the prehensory organs connected with it. Like the majority of the secreting vessels in insects, the testes are commonly slender and convoluted, and they occupy nearly the same portion of the abdomen as the ovaries in the opposite sex. Sometimes there exists only one globular body, as is found to be the case among the diurnal and crepuscular Lepidoptera; frequently a pair, and not rarely four separate ones varying in size. In their forms and disposition they vary almost without end in different groups. The ducts by which they are united to the common ejaculatory duct constitute the efferential vessels (vasa deferentia), which are usually slender throughout the greater part of the course till they become dilated into an oval or kidney-shaped bladder, which is the vesicula seminalis. The size of the latter generally bears some proportion to that of the testes, and in not a few cases it appears to be wanting. This sperm bladder terminates in a tube, joined to the corresponding one from the opposite side, forming by their union the ejaculatory duct, which is analogous in shape and situation to the egg canal of the female. Sometimes it is short and broad, at other times moderately long. The other male organs mentioned above may be considered as external. The prehensile appendages are well