On Aquatic Carnivorous Coleopteva or Dytiscidce. 867 



Group 2. 



Two closely allied species form the second group of Deronectes ; the form of the 

 body is peculiar; the elytra have their terminal portion more prolonged and 

 acuminate, and the last ventral sefrment is more elono-ate than in the members of 

 the following group. The other characters of the group have been given on p. 419, 

 and it is only necessary here to remark that as the first group of the genus agrees 

 with this second group in the separation of the hind articular cavities ; and as H. 

 tessellatus, (the third group), has the posterior tibise punctured in a similar manner, 

 it is clear that these characters do not justify the establishment of a distinct genus 

 for the second group : I expect however that characters will ultimately be detected 

 that will call for its separation as a good and distinct aggregate. 



Group 3. 



This group consists of an isolated species, with coarsely punctate hind tibiae, but 

 in other respects similar to the following or fourth group ; it would thus seem to 

 be a connecting link between the first and fourth groups, but such is not really 

 the case, and it is more correctly an insect belonging to the fourth group but 

 possessing to a considerable extent one of the more important characters of the 

 first group. It is to be noted that this exceptional species is an insular one, found 

 in the Canary Islands, and it is additionally intei-esting to find that the H. vigllans of 

 Madeira which I have placed in the following groups, has some punctures placed 

 on the basal portion of the tibia and so forms a connecting link between the H. 

 tessellatus and the fourth group. 



Group 4. 



The fourth group of Deronectes comprises the majority of the genus, and 

 includes all the species having the infero-external face of the hind tibiae glabrous 

 and shining. The group is specially well represented in the regions near the 

 Mediterranean, but includes a very widely distributed alpine and boreal species, 

 and one or two from the New World. 



About fifty species, arranged in four groups as above expressed, form the aggregate 

 Deronectes. The form of the individuals is oval, or oblong oval, and only moderately 

 convex beneath, the upper surface is very finely pubescent, and finely punctate. 

 (In most of the species, the punctuation is very fine, and the undersurface is 

 entirely without coarse punctures, but has an extremely dense, fine, somewhat 

 rugose sculpture, rendering it very opaque, and the upper surface is more or less 

 variegate in colour ; the remarkable first group forms however an exception in these 

 respects, for the surface is not variegate, and a coarse punctuation exists, to a greater 

 or less extent, in combination with the fine sculpture). 



The head is never margined in front, the epipleurse of the elytra are much narrowed 



TBAHS. SOT. DUB. SOC, N.3., VOL. II. * T 



