98 IIYDKADKPIIACwV — DYTISCIDAE. 



C C. Elytra witli only the rows of punctures 

 dark. 

 Pale red-yellow. Thorax rather deeply punctured in front 

 and behind, punctures dark ; shoulders of elytra rather 

 broader tlian in H.fvlvvs. L. If 1. Eatlier common. 



H. fl a vicoll i s, Sturm. 



2. Thorax without the row of larger punctures at 

 base. 

 Pale yellow. Thorax rather closely punctured in front 

 and behind, punctures finer than in H. Jlavkollis and un- 

 coloured ; shoulders of elytra prominent, row^s of punctures 

 dark, first puncture of live inner rows much larger than 

 the rest. L. 1-j 1. Not common. H. cinercus, Aub. 



b. Base of thorax with a small longitudinal impression 

 on each side. 



I. Punctuation of thorax rather close in front and 

 behind. 



1. Elytra with l)lack lines, somewhat interrupted 

 in places. 



Pale yellow. Shoulders of elytra narrower than in //. 

 rujicollis, first puncture in the rows not large. L. 1|- 1. 

 Common. H. fhtviatilis, Aub. 



'i. Elytra with Ijlack lines, equally broad through- 

 out. 



Yellow-brown. Shoulders of elytra much narrower than 

 'n\ II. rujicollis. L. 1^1. Dumfries. II. striatus,'^\\i\Y\). 



/>. Elytra with black lines and spots. 

 Yellow-brown. L. H 1. Common. II. rvficollis, DeG. 



II, Punctuation of thorax close in front, in other 

 parts very isolated. 



liead l)rown, antennae and pal])i yellow; thorax yellow, 

 with a l)lack longitudinal line in middle, base with a 

 ti'ansverse impression, at each end of which is a sharply 

 engraved curved line; elytra grey-yellow, with some more 

 or less distinct dark spots, sides almost in a continuous lino 

 with those of thorax, third, fourth, and fifth rows of punc- 

 tures commencing with a nnich larger puncture. L. 1| 1. 

 Common. H. lineatocollis, Marsh. 



