lfi() GEO. H. HORN, M. D. 



may be assumed as the most perfect development of the type. There is 

 a transverse band about one-third from the apex consisting of a broadly 

 crescentic division on each elytron ; these join at the suture, and extend 

 forward, forming a common sutural band broadest in front, a lateral elon- 

 gate spot is seen behind the humeral protuberance. It is easy to trace 

 the development of the markings observed in the other species from this 

 form by the interruption of the sutural stripe and a narrowing or inter- 

 ruption of the band or by an extension and suffusion of all the markings. 

 As these modifications run almost insensibly from one into another it is 

 absolutely impossible to separate species by them. In fact the markings 

 on the elytra can only be described in the most general way. 



The sexual characters give the only sure means of separating the species 

 into groups in any respect natural. It is consequently necessary before 

 attempting any study of the species to determine the sexes of the speci- 

 mens. The males have usually decided characters, the females are known 

 only negatively, having but rai'ely special characters. The males of all 

 the species have certain characters in common. The pygidium is obtuse 

 or truncate at tip, and a small additional segment is visible beyond it, the 

 last ventral is more obtuse than in the female, and is usually more or less 

 impressed or even with a large fovea {nupervs). 



In five species the male elytra are obliquely truncate, so that the sutural 

 angle is retracted, the outer angle formed by the truncation is sub-spincjus. 

 In the other species the elytra are separately or conjointly rounded. One 

 species (^calcaratus) has a well marked tooth near the middle of the inner 

 side of the front tibiae. The thoracic horn is usually narrower and more 

 parallel in the male, but this is not always easy to detect, and in (tnchora 

 absolutely fails. 



In the females very little has been observed. The tips of the elytra 

 are very distinctly truncate in falpa, and in anchora nearly as much so. 



In four of the species the elytra are impressed behind the base, as a 

 general rule more distinctly in the males than in the females. 



The vestiture of the surface is of two kinds, — a fine, short, recumbent 

 pubescence, and a coarse hairyness. With the former it is rare to see 

 any erect hairs, and then they are very inconspicuous, while in the 

 coarsely hairy species long erect hairs are constantly present. 



The thoracic horn, as already stated, varies with the sex in its form. 

 Within specific limits there is considerable variation in the degree and 

 extent of the serration of its margin, so that it is as useless to attempt 

 the separation of species on this basis as on the elytral markings. 1'he 

 crest varies usually less than the horn, but from a fair degree of promi- 



