152 ADEPHAGA. [^HciUplnS. 



2. Head narrow ; thorax strongly contracted in 

 front. 



A. Anterior margin of thorax truncate in middle; 

 elytra pale yellow without dark spots ; thorax 

 with a distinctly defined row of large punc- 

 tures at base H. flavicollis, Sfnnn. 



B. Anterior margin of thorax slightly produced 

 in middle, sinuate ; elytra (as a rule) reddish 



with dark spots. 



a. Thorax with a distinctly defined row of 

 large punctures at base ; humeral angles not 



prominent. 



a*. Form oblong-ovate ; punctuation of an- 

 terior part of thorax distinctly feebler 

 than of base H. FULVUS, i?'. 



b*. Form short oval ; punctuation of anterior 



part of thorax as strong as of base . . . H. TARIEGATUS, Sturm. 



b. Thorax without a distinctly defined row of 

 large punctures at base ; humeral angles 



prominent H. CINEEEUS, Aitbe. 



ii. Thorax with an impressed longitudinal stria on 

 each side. 



1. Thorax without longitudinal black line in centre, 



its base not channelled. 



A. Shoulders broader, colour darker, sides of 



elytra less parallel H. EUFicoLLis, i)e (?. 



B. Shoulders narrower, colour lighter ; sides of 



elytra more parallel. 



a. Elytra with dark lines more or less inter- 

 rupted by dark spots H. flutiatilis, Auhd. 



b. Elytra with dark lines never intei'rupted by 



dark spots H. steiatus, Sharp. 



2. Thorax with longitudinal black line in centre, 



its base deeply channelled H. lineatocollis, Marsh. 



K. obliquus, Er. {aracenus, 01.). Testaceous, somewhat dull, wliolo 

 upper surface extremely finely and thickly punctured ; hack part of head 

 and middle of anterior margin of thorax (usually more or less) black or 

 fuscous ; thorax double as broad as long, strongly contracted in front, 

 with rather diffuse and strong punctures in middle and at base ; elytra 

 at base broader than base of thorax, acuminate at apex, with rows of 

 fine punctures which stand on interrupted black lines ; viewed as a whole 

 the base, suture, a broadly waved baiid across middle, and four spots 

 (two on each elytron, usually confluent) just before apex appear black ; 

 legs testaceous. L. 3| mm. 



Found both in ponds and ditches, and also in running water; somewhat local, but 

 widely distributed throughout England ; in Scotland it is rare, and only occurs in 

 the Tweed and Forth districts. Ireland, Dublin and Armagh, and probably widely 

 distributed. 



21. confinis, Steph. {lineatus, Aub(5). Very like the preceding, but 

 distinctly broader at the shoulders, and usually of a darker reddish 

 colour ; it is easily distinguished from that species by the short longi- 

 tudinal stria on each side of base of thorax ; thorax entirely testaceous 

 or with anterior and posterior margins more or less narrowly dark ; elytra 



