NO. 1170. THE FAMILY GOMFHODESMIDJi— COOK. 705 



In this geuiis the copiilatory lejrs are again constructert on the plan 

 followed hj AstrodeHinuH awd Aulodesmns^ but with some unique feat- 

 ures. The basal part of tlie trigonal second joint is greatly reduced, 

 while the node is curiou.sly develoi)ed, being constricted at its base and 

 borne as a projection from the anterior (by flexure posterior) face of the 

 antico-postically compressed structure; the two spines described in 

 oxyyontis are still recognizable, being located ac the base of the nodus 

 and flagellum. The nodus bears in addition, however, two small coni- 

 cal spines on its lateral face, and two which [)r<)ject against and are 

 covered by the upright part of the compressed portion at the begin- 

 ning of the curve, and also another, large, strong, and curved, which 

 is directed mesad at first, and curves around the base of the compressed 

 portion. The tiagellum is broad and comi>ressed at the base, but is 

 soon abruptly narrowed, although still compressed; it curves in nearly 

 a circle, crossing its fellow, is bifid near the apex, the larger division 

 taking a spiral turn and being again bifid. Thus, while the plan is 

 evidently tlie same, the details are nearly all different. 



Although the first segment is in reality proportionally longer than 

 in the other genera, the relation between the length and breadth is 

 some\vhat affected by the fact that it is very strongly convex, so that 

 the carime are decurved and do not project laterad. If the segment 

 were flattened out it would be as broad as any on account of its pro- 

 duced lateral corners. 



The segments are more convex, and more evenly so, with the surface 

 more highly polished, and the posterior corners of the carinte less pro- 

 duced than in the other large genera with which it is compared. 



The maiginai callus, though distinctly broad on anterior segments, 

 does not taper abruptly cephalad as in Omodesnius oxygonusj the mesial 

 edge being more nearly longitudinal. 



GOMPHODESMUS CASTANEUS Cook. 

 (Plate LVIII, figs, la-ll.) 

 GomphodesmiiS castaneus CooK, Proc. U. S. Nat. Mus., 1895, XVIII, p. S3. 



The vertex is without hairs, highly polished and shining; sulcus dis- 

 tinct, ending below in a considerable de[)re8sion which is connected 

 with the antennal sockets by suboblique, finely rugulose, scarcely 

 depressed lines. 



Olypeus also polished and shining, evenly convex, the lateral depres- 

 sions very slight, with a few oblique sulci, a pair of minute punctations 

 somewhat below the level of the antennal sockets, and a somewhat 

 irregular transverse row of about ten above the labrum. 



Labrum inserted much below the level of the clypeus, the anterior 

 edge transverse, the emargination very narrow and slight, the teeth 

 very small. 



Guathochilarium hirsute with fine, short hairs. 

 Proc. N. ]M. vol. xxi 45 



