NEW BRITISH SPECIES, ETC., IN 1868. 49 



tion of B. cerasurum, and was compelled to come to the con- 

 clusion that all my exponents of that insect were ruhidusj 

 (Gyll.) Schon., iii, 384, 12, and that Mr. Wilkinson's speci- 

 men was the true cerasorum, Hbst. Curiously enough, Dr. 

 Sharp informs me that Mr. G. R. Crotch and himself had 

 also come to the same conclusion as to the ordinary cera- 

 sorum of our collections. Mr. Crotch has also, I believe, 

 found what are apparently male and female of true ce)'asorum, 

 mounted on one card, among the series of the supposed 

 species of that name in the Brit. Mus. English Collection, 

 the remainder being what I considered rubiduSy and one of 

 the cards at least having apparently the sexes mounted on it. 

 In none of my old cerasorum is the rostrum much longer, 

 and in one of them it is perceptibly shorter, than the head 

 and thorax ; whereas, in the true cerasorurriy it is of much 

 greater length, in the female exceeding the whole length of 

 the body. Besides this character (mentioned at length by 

 Herr Fuchs, who compares rubidus and cerasorum m Berl. 

 Ent. Zeit., 1862, 426), the posterior femora in the latter in- 

 sect are armed with a distinct, sharp, small tooth ; and the 

 entire beetle is of a different build to that which has the non- 

 dentate femora, being larger as a rule, wider, flatter, morje 

 suddenly contracted behind, more variegated, and altogether 

 more resembling a little B. turbatus, or one of its allies. So 

 far, one would imagine that the two species were satisfac- 

 torily discriminated; but there is equally strong and per- 

 fectly reliable evidence that the two beetles are simply the 

 sexes of one species ! Mr. F. Smith, whose habits of accu- 

 rate observation are well known, has several pairs, taken by 

 himself in cop., and carefully mounted ; all the females of 

 which are cerasorum and all the males 7'ubidus; and Dr. 

 Power has taken several rubiduSy unaccompanied by the 

 other form, off a particular birch-tree, upon which, some 

 1869. E 



