Casey — Observations on the StnphyUnidae. 357 



truncate aud bearing at tip the small transverse, usually finely 

 emarginate or deeply, narrowly cleft labrum. In the Meto- 

 ponci the epistoma is singularly prominent dorsally and can- 

 aliculate, and, in the Diochi, the labrum is entire and even 

 finely denticulate at the middle. The mandibles are moderate 

 in size, dentate within and variously modified on the exterior 

 surface, which is either entire as in Eulissus^ grooved as in 

 the majority of the Xantholini or with a sinuous stria as 

 in Metoponcus, with rounded external edge, as a rule, or with 

 an acute edge as in Diochus. The maxillary palpi vary 

 greatly, having the third joint long or short and the fourth 

 correspondingly short or elongate, finely aciculate and very 

 slender to conical and gradually pointed ; they are always 

 coarsely setulose and glabrous, except in Diochics, where they 

 become finely and closely pubescent as well as setulose. The 

 labial palpi are usually simple, with slender third joint, but in 

 the neotropical Araeocnemis have the third joint, singularly 

 enlarged. The mentum is usually transverse, becoming espe- 

 cially modified only in the very remarkable genus Plaly- 

 prosopus. 



The elytral suture is abnormal in the Xantholini, and, to, a 

 much less marked degree, in the Araeocnemes and Metoponci, 

 the inner edge of each elytron being widely and gradually 

 beveled, so that in closing, one slips upon the other to a slight 

 extent, leaving the summits of the beveled edges as two sep- 

 arate broadly arcuate lines, a formation which enables one to 

 identify a Xantholinid at a glance, even without noticing the 

 aberrant antennae. A number of subtribes have the elytral 

 suture normal, however, such as the Othii, Diochi and those 

 which follow in the table below. The neck is usually rather 

 thick, and, although sometimes narrow, never becomes so 

 extremely slender as in Stilicus and some other genera of the 

 Paederini for example. The anterior and middle coxae are 

 remarkably large and prominent as a rule, but the posterior 

 have the exposed inner parts small and contiguous as usual. 

 In many forms, such as the Hyptiomae, the middle coxae 

 become flat on their exposed surface when in repose ; they 

 frequently extend from the median line to the sides of the 



