NORTH AMERICAN APTERYGOGENEA. 1 75 



Gen. III. Cremastocephalus n. g. 

 (Derivatio /tpi/j.ad&ai and xs<pakr;) 

 Cremastocephalus trilobatus n. sp. 



The head is hanging down. The thorax is curved. The 

 mesonotum covering the pro not am, but not projecting over 

 the posterior part of the head. The fourth abdominal 

 segment occupying the half of the body. The antennce are 

 nearly twice as long as the body, ^.jointed, with the basal 

 joint strongly developed. The eyes are sixteen, eight on 

 each side of the head. The tibial tenent hair is enlarged 

 at the end. The upper claw is furnished with two teeth, 

 extremely fine. The lower claw is obliquely cut off at the 

 end. The denies of the furcula are nearly of the same 

 width all along. The -macro widely rectangular, running 

 out into three large points, and furnished with a scale, 

 hanging down in front. Scales wanting.. Length ? mm. 



This genus, on a superficial inspection, seems to join 

 characters derived from two genera before set up by me, 

 the Campylothorax and Trichorypha. To the former it 

 has some resemblance in the curved thorax and in the 

 strongly developed basal joints of the antenna?; to the 

 latter in the shape of the mucronal segment of the furcula. 

 From Campylothorax, however, it may easily be distin- 

 guished by the following characters : 



(1) The shape of the mesonotum. (2) The number 

 and disposition of the eyes. (3) The shape of the mu- 

 cronal segment, and (4) The absence of scales. From 

 Tricorypha it is to be distinguished by (1) the curved 

 thorax; (2) the disposition of the eyes, and (3) the ab- 

 sence of scales. 



The head is hanging down and the thorax curved, so 

 that the form, as I said, on a superficial inspection, looks 

 like a species of Campylothorax. The curvation of the 

 body, however, is not produced by the angular mesonotum, 



