NP:\Y MAl.I.orilAGA. 



203 



tlie ventral pjirt of the base of tin- penis. It may, 

 therefore, be represented as in fi^urt' 5, jil . Tliis inter- 

 nal strueturc may be short or long and either narrow or 

 broad, but it is always essentially the same and lies yen- 

 tral to the ductus ejaculatorius. The external parts are 

 developed as various degrees of ohitinization radiating 

 tlirough the waits of the penis from the ventral basal 

 chitinous deposit. The simplest and most usual form 

 consists of a rod given off backward on each side (lig. 

 6) such as in Menopon inesolev.cuni, Trlnoton luridum, 

 Colpocephaluia osborni, and others. 



Figs. 6-8. — Diagram sbowiug successive degrees of chjtfuixation lu walls of peuis: 

 p, peuis; gc, genitiil cliambtTs; ;>/. internal i)la'e. 



Secondary processes may be developed from these. 

 In others the basal chitin may completely surround the 

 penis (fig. 7) and, besides lateral jtrocesses, may give 

 ofF dorsal an<l ventral ones as in Goaiotles cervinicornis. 

 Further, this circular basal chit inizalion may extend 

 continuously backward (lig. 8) and transft»riu the penis 

 into a chitinous tube, as in DocojihorKs hd'i and in Knr;f- 

 inetopns taio-Hs:. 1 lulepeiulcnt ehitini/.ations may also 

 be developed in the penis, taking the form of plates 

 and granulations in its walls, as in Li/tciirux /uli(fino!iii< 

 iiHiJor. It cannot be slated wlietlier the articulated lat- 

 eral processes are homologou> with the non-articulated 



