6o SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 82 



Pararncren.- — In Gnathotrichus the parameren (Pa) is a heavily 

 chitinized ringlike structure. It is entire, without a dorsal transverse 

 suture or knoblike projection cephalad, as in Pityogenes Bedel, and 

 was called umbellicus by Fuchs. Ventrally. a faint suture is visible in 

 Gil. sulcatns Lee. and retusus Lee. only. A prominent, heavily chiti- 

 nized hook extends cephalad from the ventral suture. This structure 

 was called the metula (Me) by Fuchs and the apodemal process by 

 Hopkins. In Gn. retusus Lee. and sulcatns Lee. a second, caudad, 

 but much smaller knob (a) is present. The tegmen furcae (Fuchs) 

 (b), which are a lateral continuation of the metula, are weakly de- 

 veloped. Lateral widenings of the parameren, Seitenfluegel (Fuchs), 

 are absent. 



Specific modifications: — • 



A — Parameren without small knob ventro-caudad ; metula long but 



slender. Gn. tnateriarius Fitch. 

 AA — Parameren with small knob ventro-caudad ; metula variously 



modified. 



B — Metula short, weakly developed. Gn. retusus Lee. 



BB — Metula long, strongly developed. Gn. sulcatus Lee. 



Inner covers. — The inner cover (Fuchs), the body (Hopkins), the 

 penis tube (Nuesslin) is a tubelike structure, bilateral-symmetric. On 

 the inner covers three main parts may be distinguished which are the 

 lamina dorsales (Lad), the laminae ventrales (Lav) and the peduculi 

 penis (Fep). The dorso-caudad portion of the inner covers was called 

 the Endplatten by Lindeman, the laminae dorsales by Fuchs and the 

 dorsal plates by Hopkins. The laminae ventrales (Fuchs) or ventral 

 plates (Hopkins) are the corresponding ventral portion of the laminae 

 dorsales. In the genera Pityogenes Bedel, Ips de Geer, Pityokteines 

 Fuchs, Neothomicus Fuchs, and others, the laminae dorsales and ven- 

 trales are largely separated by deep emarginations caudad giving the 

 laminae the shape of four free projections which are connected basally 

 only. The basal, fused, entire part of the laminae ventrales is the 

 pallidium (Fuchs (Pal)). The sometimes narrow band connecting 

 the two dorsal plates is the jugum or Steg (Fuchs). In Gnathotrichus 

 the laminae dorsales and ventrales are fused laterally. Dorsally, the 

 two laminae dorsales are separated by an obscure suture only. The 

 laminae ventrales are fused ventrally, open on the extreme caudad 

 portion. The laminae dorsales as well as the laminae ventrales bear 

 numerous sensory pores on the caudad half. The latter is strengthened 

 by a stronger chitinized band, the caudad limitation of which (c) is 

 strongly emarginate. This chitinous strengthening was called the 



