DYTISCUS. 123 



If. Elytra olivo-l)liick,\vith side margin and numerous 

 fine longitudinal lines yellow. 



Head and thorax olive-black, all the margins of latter 

 yellow ; under-side yellow, with some more or less distinct 

 dark spots. Process of posterior coxae sharp. Elytra of 

 female furrowed until near apex. L. 12 1. Rare. 



D. lap'ponicus, Gyll. 



a. Posterior coxae with a rounded process behind. 



((. Under-side pitch-black. 



Upper-side olive-black, side margins of thorax and elytra 

 yellow. Elytra of female furrowed until beyond middle. 

 L. 12 1. Common. D. p2i7ictulatics, Fah. 



b. Under-side yellow. 



Upper-side dark olive-green, side margins of thorax and 

 elytra yellow. Elytra of female furrowed until beyond 

 middle. L. 15 1, Not common. D. dimidiatus, Berg. 



Aciliiis, 



A. Posterior femora without any black spot. 



Similar to A. sulcatvs, but rather narrower, with yellow 

 much more predominant on abdomen, and with posterior 

 tibiae and tarsi reddish. Tn female, the shallow depres- 

 sions on thorax not hairy and third furrow on elytra 

 narrower. L. 6| 1. Moderately common. 



A. canaliculatus, Nic. 



S, Posterior femora with a black spot at base. 



Broad oval, flat. Upper-side blackish-brown ; mouth, 

 margins of thorax and a transverse band in its middle 

 yellow ; under-side black, ])rosternum and lateral spots on, 

 and apical margins of abdominal segments yellow ; front 

 pairs of legs yellow ; posterior femora yellow, with a black 

 spot at base, their tibiae and tarsi pitch-black. L. 7| 1. 

 Common. A. sulcatus, Lin, 



The variety scoticus, Steph., has the thoracic band inter- 

 rupted in middle, outer margin of elytra clouded with 

 brown, abdomen with small yellowish spots on the sides 

 and its seumeuts edued with dull red. 



