212 ANATOMY". 



be derived from the following particular description of it in individual 

 insects. 



In Carabus (C. glabratus, Fabr., PI. XXV. f. 14.), in which the 

 withdrawn penis extends to the commencement of the thorax, the prae- 

 putinm extends only to the end of the fourth segment (the last connate 

 one counted as two) ; it is wide, bag-shaped, truncated at its extremity, 

 and is supported by two fine bones, which have the same shape as the 

 bag. At the base both bones lie closely together, but they with their 

 shanks so separate that the two shanks of the upper one pass to the 

 upper valve of the cloaca, and those of the lower one to its lower valve. 

 The basal portion of the penis projects beyond the upper portion of the 

 bag, driving this before it, so that it is covered by a continuation of it. 

 Besides, the sides of the bones stand in close connection with the exte- 

 rior integument by means of muscles, which hold the prepuce back 

 when the penis is pushed forward. Three horny pieces are also found 

 in the case of the bag, one heart-shaped one beneath, exactly between 

 the shanks of the bone, and the two others at the apex of the upper 

 portion which clothes the free part of the penis. There are likewise 

 bony processes which support the case of the produced part of the bag, 

 and stand in flexible connection with the horny sheath of the penis. 

 The apex of the produced portion of the bag is divided where the upper 

 end of the penis lies, and through this aperture the ductus ejaculatorius 

 seminis passes into the latter. 



The penis itself is a gently bent, horny cylinder, above round, dis- 

 tended towards its end, and flattened with obliquely truncated extre- 

 mities ; upon its lower or ventral side it has a longitudinal aperture, 

 which is surrounded by a callous margin, which indicates the outlet of 

 the ductus ejacnlatorius. 



Dyticus (PI. XXV. f. 5 10.) displays already important differences. 

 The two valves which form the cloaca are much larger, the upper one 

 is soft and ovate, the lower one harder, larger, and longitudinally 

 divided into two lobes. Both lobes are placed upon a transverse horny 

 piece', one wing of which encompasses the exterior margin of each lobe, 

 and is bound to it as well as to the ventral plate by strong muscles. 

 The prepuce of the penis lies between these two valves, which, as 

 in Carabus, is a membranous bag, but the horny bones of which are 

 differently formed, and display stronger muscular connections. The 

 prepuce itself is held distended by two horny pieces. A broad horny 

 arch, shaped to the bag, surrounds its whole circumference, but lies 



