204 [J^'y- 1801. 



tion, and form a much more important character than the margination 



of the thorax on which Kuwert and other authors base their chief 



divisions. 



Dr. Horn gives the characters depending upon those ridges as 



follows : — 



Stridulating ridge of first ventral segment incomplete, i. e., extending from the front 



angle in a curved line merely to the posterior border of the segment... 



Heterocerus. 



Stridulating ridge of first ventral segment complete, i. e., forming nearly a semicircle 



from the front angle to the posterior border, then recurving to the inner 



coxal border Littorimus. 



As far, however, as our fauna is concerned, this character is not 

 of much use, as the subgenus Littorimus only contains two species, 

 H. hritannicus and H. sericans, and it is doubtful whether the latter 

 species can really be regarded as British ; it seems, therefore, that we 

 must, to a certain extent, fall back upon the character presented by 

 the margiuatiou of the posterior angles of the thorax, in spite of its 

 being so unsatisfactory. H. Jlexuosiis, femoralis, salinus v. rectus, and 

 arenarius, will be found to present scarcely a trace of margins, whereas 

 in the other species they are more or less distinctly visible. 



Dr. Sharp (Biol. Cent. Amer., vol. i, pt. 2, p. 116) makes use of 

 a character which he has recently observed, and which may prove to 

 be of considerable importance. In several of the American species 

 there is an elevated line on the metasternum, which begins at the 

 middle of the posterior border of the middle coxa, extending obliquely 

 backward and joining the suture between the metasternum and its 

 episternum ; it is possible that this may prove a good character with 

 regard to some of our species, but I have not been able to observe it in 

 those that I have examined. The shape of the labrum and mandibles 

 in the male will also be found to present marks of distinction ; the 

 sculpture of the elytra will be seen to vary much in the same species, 

 some specimens being more plainly substriate and more coarsely punc- 

 tured than the others. When we take intx) account the great differ- 

 ence that also exists in the markings of the same species, it will at 

 once be seen how very easily confusion may arise : the clothing 

 consists of a more or less dense, short, semi-erect pubescence, the 

 margins being set with longer hairs, which are more conspicuous on 

 the thorax. 



The males are, as Dr. Horn observes, in most cases easy to dis- 

 tinguish from the females ; the head is larger and more prominent, 

 the mandibles more slender and projecting, the labrum longer, and 

 the clypeus retuse to a varying degree ; the thorax is at least as bi'oad 



