74 o THE GENERATIVE ORGAXX. 



sternum in front and with the sides of the penis internally. 

 They are undoubtedly the homologues of the great claspers of 

 the male Hymenoptera, and of the so-called external sheath of 

 the penis. Their position immediately behind the progenital 

 sternum shows that they are the lateral appendages of the 

 progenital or mesogenital somite, and their developmental 

 history, as well as the position of the claspers in the Hymen- 

 optera, renders it almost certain that they are appendages of 

 the progenital somite. 



In this case they clearly correspond with the inferior blades 

 of the ovipositor in Locusta viridissima. 



The Penis in the Muscidae is a very complex organ. It con- 

 sists of a membranous, papilla-like projection from the thin 



Fn.. 105. A transverse section of the penis of a Llow-fly. ///, hypophallus ; 



//>, paraphallus. 



integument of the roof of the genital sinus, at the extremity of 

 which the ejaculatory duct opens externally. 



This membranous papilla contains a large blood sinus and is 

 capable of erection ; it is supported and protected by a com- 

 plex chitinous framework, which consists of a pair of para- 

 phalli enclosing its base, and of a large, curved, ventral plate, 

 which I shall term the hypophallus. 



I I KM KIITION 01 I'l \ I I. I- II. 



View n( the penis from its under surface ; l>, bulb ; A r . anterior gonapophyses ; ///, 

 hyp- 'phallus ;/A paraphallus ; o, orifice of ejaculatory duct ; r, ridges of epipleura. 



