Royal Physical Society. 75 



The number of species at first described was small. Latreille 

 in his ( Hist. Nat/ only describes three, and in his f Genera 

 Crustaceorum et Insectorum/ published in 1807, he describes 

 five. He there breaks the genus into two groups, one corre- 

 sponding to the subgenus Choleva, of which he describes the 

 species agilis and angustatus, auct., and the other including the 

 rest of the genus. 



Gyllenhal in 1808 published six species in the first volume of 

 his ( Insecta Suecica/ 



It is unnecessary to enter into any examination of the syno- 

 nymy of the species described by these authors. Their descrip- 

 tions are for the most part too vague and applicable to too many 

 species subsequently described to allow us to rely greatly upon 

 them. Gyllenhal in his 4th volume, which was not published 

 till 1827, acknowledges that in his 1st volume he had included 

 five different species under one name. 



Mr. Spence was the first author who brought the genus into 

 something like order. 



In his Monograph (published in the Linnsean Society's 

 Transactions in 1815) he divided the genus into three main 

 sections, dependent upon the antennse being filiform or clavate, 

 the posterior angles of the thorax obtuse or acute, and the 

 elytra striate or not striate ; the dilatation or non-dilatation of 

 the first article of the middle tarsi in the males was also made 

 a subordinate character. Of these, the first and last are the 

 only ones which have been adopted as sectional characters by 

 subsequent authors ; but the form of the hinder angles of the 

 thorax, although not a good sectional character by itself, will, I 

 think, if taken in conjunction with the base of the elytra, be 

 found to furnish good characters for natural subdivision. Mr. 

 Spence groups his species under the above sectional characters 

 (to each of which I shall attach the synonym now most in use) 

 as follows, viz. : — 



* Antenna subfiliform ; posterior angles of thorax obtuse ( = Sub- 

 gen. Choleva, Steph.). 



C. oblonga = angustata, Fab., Erich. 

 C. agilis — agilis, 111., Erich. 



** Antennce clavate ; posterior angles of thorax acute ; elytra for 

 the most part striated ( = Subgen. Catops, Steph.). 

 (Anterior thighs for the most part thickened at the apex in the 

 males, and first article of middle tarsi dilated.) 



a. Basal margin of thorax excised near the angles. 



C. nigricans = nigricans, Erich. 



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