460 APPENDIX. 



to the American species : " Considerable stress has been laid on the fact 

 as to Avhether the base of the thorax has a marginal line, but as far as 

 our species arc known it exists in all, but varies in the sharpness of its 

 definition." 



The first two sub-genera, mentioned in Kuwort's paper, are not repre- 

 sented in Britain : these are Micilu?, Schiodte (containing a single 

 species, M. murinus, Kies.) and PJnjriies, Schiodte (containing a single 

 species, P. aureolus, Schiodte) ; the former is distinguished by the shape 

 of the scutellum (which is punctiform and subtransverse) and the latter 

 by having the third joint of the antennae small and the fourth forming 

 with the following a uniform club, whereas in Heterocerus and Tcenhe- 

 tocerus the third and fourth joints are both small. 



Kiesenwetter appears to have been the first who attempted to mono- 

 graph the species, and he divided them chiefly on colour and sculpture, 

 both of which are very misleading characters, as both vary considerably 

 in different specimens of the same species ; Schiodte in 1866 attempted 

 a division on obscure antennal characters; in 1872, however, Mulsant 

 and Rey observed that in certain species the elevated curved line on the 

 first ventral segment extended from the front angle by a broad curve 

 towards the middle of the posterior edge of the segment and there ter- 

 minated, while in others the line continued the curve forward towards the 

 inner edge of the coxae ; these lines are apparently stridulating organs, 

 and the genus is divided by Dr. Horn on this character 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, i. sp. 

 Stridulating ridge of first yentral segment complete, 



i.e. forming nearly a semicircle from the front 



angle to the posterior border, then recurving to the 



inner coxal border LITTORIMUS, Des Gozis, 



The latter division was originally wrongly named Augyles, which was 

 the name applied by Schiodte to quite a different division, founded, as 

 above-mentioned, on obscure antennal characters. 



As far as our fauna is concerned the characters depending on these 

 stridulating organs are not of much practical use, as the sub-genus Littori- 

 mus only contains two species, 11. britannicus and H. sericans, and it is 

 doubtful whether the latter species can really be regarded as indigenous ; 

 it seems, therefore, that we nmst to a certain extent fall back upon the 

 character presented by the marginalion of the posterior angles of the 

 thorax, in spite of its being often so unsatisfactory ; H. flexuosuc-, 

 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. Am. 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 



