A Review of the North American 

 Species of Agabus 



Together with a Description of 

 a New Genus and Species of Agabini 



By H. C. FALL 



The genus Agabus, in the broad sense in which it is used by Sharp, 

 and to which American students have become accustomed, includes, 

 next to Hydroporus, a greater number of species than any other genus 

 of North American Dytiscidae. Not since the appearance of Sharp's 

 Monograph in 1882 has any general survey of our Agabi been offered, 

 and the arrangement of species in both the Henshaw and Leng Lists 

 is substantially in accord with Sharp's treatment. 



First and last a considerable number of genera have been established 

 at the expense of Agabus, most of which are rejected, at least in the 

 full generic sense, by Sharp. In a restricted sense nearly all our 

 species belong to Gaurodytes of C. J. Thomson, under which name 

 they were treated by Crotch in his Revision of 1873, and which has 

 recently been fully accepted by Zimmermann. Sharp does not accept 

 this and other genera, for, as he says, Thomson "unfortunately relied 

 largely on one (character) which is very unsuitable for the purpose 'of 

 arriving at a natural classification; I am alluding to the size and 

 form of the wings of the metasternum ; so variable is this character 

 that scarcely any two species can be found agreeing as to it, and 

 on the other hand, species which are nearly or quite conformable as to 

 this, are really by no means naturally allied by their other characters." 

 Of typical Agabus, as represented by the serricornis of the Palearctic 

 fauna, we have the single species clavatus Lee., which like serricornis 

 is remarkable in having the apical joints of the antennae in the male 

 dilated and compressed, and has the metasternal laciniae relatively 

 narrow, this latter character however being less extreme in clavatus 

 than in serricornis. Two species cordatus and rectus peculiar by 

 the small nebrioid form of thorax, have been by LeConte and Crotch 

 referred to Anisomera Brulle founded upon a Chilian species of small 

 size and flavate color. Although quite unacquainted with the South 

 American insect, this reference seems to me extremely questionable. 

 It is probable however that these two species belong to Hydronebrius 



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