634 On Aquatic Carnivorous Coleoptera or Dytiscidce. 



The characters of the male are similar to those of H. shuckardi, except that the 

 circular plate formed by the three dilated joints of the front tarsi is not quite so 

 large and broad, and the four palettes near the base are not so much larger than 

 the others. 



The species is closely allied to H. shuckardi, but is easily distinguished ; it is a 

 little broader, and (besides the difference in the sides of the thorax of the two 

 species) in the one now under consideration the wing-cases have a slight explana- 

 tion of their lateral margins near the apex, and their outline is not so continuous 

 with that of the thorax, and the scattered punctures are more conspicuous. The 

 corresponding sexes of the two should be compared, in order that the sexual 

 differences in the outline of the thorax should be allowed for. I have not yet seen 

 a rufifose form of the female. 



d 



Australia, (King George's Sound, West Australia). 93.3. 



982. Hyderodes collaris, n. sp. — Ovalis, robustus, convexus, piceo-niger, clypeo, 

 prothoracis lateribus antennisque rufis, pedibus piceo-rufis ; prothorace lateribus 

 baud discrete et parum crasse marginatis, sed intra marginem conspicue depresso ; 

 elytrorum humeris praminulis ; prosterni processu angusto. Long. 19, lat. 11 m.m. 



I have seen only a single individual of this species, it is a rugose female ; the 

 prominent shoulders and the very narrow and contracted prosternal process and 

 metasternal groove, will easily lead to the recognition of the other forms of the 

 species when they are discovered. 



North-west Australia. 934. 



1. 66.— Genus Dyr/SCf/S. 



Clypeus entirely yellow, the yellow colour sharply limited in a straight line from 

 the dark colour of the front of the head. Clypeal suture entire, thoush sometimes 

 so indistinct in the middle as not to be perceived at first glance. Elytra with a 

 yellow lateral stripe. 



The species* are characteristic of the northern parts of the Old and New Worlds, 



• The following species' descriptions also refer to this genus : Dytiscus anxius, Mann. (No. 1,285 huj. 

 op.); North America. — Dytiscus confusus, Motsch. (No. 1,287) ?=No. 99.5; Siberia. — Dytiscus front- 

 alis, Motsch. (No. 1,291); Kamtschatka. — Dytiscus fusco-striatus, Motsch. (No. 1,292) j North America. 

 — Dytiscus ibericus, Eos. (No. 1,293); Spain. 



