NO. lO MORPHOLOGY OF GNATHOTRICHUS SCHEDL 6l 



radius by Fuchs and this is well developed in all three species of 

 Gnathotrichus. A corresponding strengthening on the laminae dor- 

 sales, which as the manubrium (Fuchs) is well developed in the genus 

 Pityogencs is obscure in Gimthotrichus. The caudad portion of the 

 laminae ventrales, the caput (Fuchs), is variously modified, sometimes 

 bearing a beaklike projection dorsally which was called the rostrum by 

 Fuchs. The caput and rostrum vary considerably in shape and de- 

 velopment in the genus GnatJiotrichus. The area of the pallidium, 

 from which the peduculi penis originate, the radix (Fuchs), is not 

 characterized by a heavier chitinization. The peduculi penis were also 

 called Fuesschen by Lindeman, femora penis by Verhoefif and body 

 apodemes by Hopkins. In the normal position the peduculi penis are 

 parallel ; when mounted on slides they usually cross each other. 

 Cephalad the peduculi are slightly widened, their connection with the 

 pallidium is solid, not hingelike. 



Enclosed parts. — The enclosed parts are a short part of the ductus 

 ejaculatorius, the preputial sac and chitinous strengthenings of the 

 latter. The ductus ejaculatorius is easily recognized by its enclosing 

 muscle structure. The author was able to trace this structure as far 

 caudad as the radius (c) extends. The preputial sac fPrp) consists 

 of a colorless membrane without any chitinous strengthenings. It 

 seems to be connected with the ductus ejaculatorius at the anterior 

 emargination of the radius. Chitinous structures such as the Rinne 

 (Fuchs) do not occur in the genus Gnathotrichus. 



Parts outside of the covers. — It was stated in the introduction to 

 the discussion of the penis that no indications of the spiculum ventrale 

 are present in the genus Gnathotrichus. While in Xyloterus Er. and in 

 some genera of the European Hylcsinidac. the reduction of the Rinne 

 (Fuchs) mostly is followed by a stronger development of the spicu- 

 lum ventrale, Gnathotrichus presents a complete reduction of both. 



Generic characters of the penis. — Spiculum ventrale absent ; para- 

 meren an entire ring, metula well developed ; laminae dorsales and 

 ventrales fused laterally, the laminae dorsales dorsally separated by 

 an obscure suture, the laminae ventrales fused except on the extreme 

 caudad portion, the laminae forming a tube, radius distinct, manu- 

 brium obscure, jugum and pallidium not clearly defined ; sensory pores 

 on the caudad half of the laminae dorsally as well as on the laminae 

 ventrales ; the latter always extending farther caudad than the former ; 

 the peduculi penis slender, slightly widened cephalad, about as long 

 as the laminae dorsales, connection with the pallidium solid not hinge- 

 like; Rinne absent, preputial sac about as long as half of the laminae 

 ventrales. 



