NO. 10 MORPHOLOGY OF GNATIIOTRICHUS SCIIEDL 57 



Lateral onarci'nuition. — The lateral emargination (Hopkins) (fig. 

 17, p) is an emargination on the scntnm on the lateral margin of the 

 scutellar lobe in which is implanted the inner posterior lobe of the 

 scapular plate and the scapular hook. The latter connects the pos- 

 terior prealar process with the scapular plate and the scutellar lobe, 

 respectively. 



The Male Reproductive Organs 



The male reproductive organs consist, as shown by Nuesslin for 

 this family, of elements of endodermal and of ectodermal origin. 

 These two groups of elements are separated in the larvae and be- 

 come connected during the pupal stage. Of endodermal origin are 

 the testi (fig. 31, Te), the vasa deferentia (fig. 31, Vd) and the 



Fig. 31. — Gnathotrichus materiarius Fitch: Male reproductive organs. 



Dej, ductus ejaculatorius; Gl. ace, accessory glands; Pen, penis; Te, testi; Vd-d, vasa 

 deferentia, duplex; Vd-s, vasa deferentia, simplex. 



mesadenic, or mucous glands (fig. 31, Gl. ace). On the other hand, 

 the seminal vesicle (in part, fig. 33, Rec), the ductus ejaculatorius 

 (fig. 31, Dej) and the penis (fig. 3, Pen) are of ectodermal origin. The 

 point of connection of these elements is plainly visible in the adults. 

 The distal part of the vasa deferentia and the mucous glands join a 

 short, usually narrow tube, " Zunge " (Nuesslin) ; the latter connects 

 with the ductus ejaculatorius. Externally the Zunge, an endodermal 

 structure, is encircled by a wider tubelike or sphericle envelope, which 

 consists of two parts, the distal end or " Mantel " (Nuesslin) of en- 

 dodermal, and the basal part or " Becher " (Nuesslin) of ectodermal 

 origin. These last mentioned structures are seen commonly as a ball- 

 like widening of the ductus ejaculatorius and are usually called the 

 seminal vesicle. 



The following description is based on Gnatlwtrichus materiarius 

 Fitch only. 



