718 On Aquatic Carrdvorous Coleoptera or DytiscidcB. 



bus, elytris subtillter transversim corrugatis, tuberculisque omnium minutissimis 

 elevatis. Long. 25, lat, 14 m.m. 



This species is very closely allied to C. sugillatus, but is much larger and 

 broader, and has the surface of the elytra more rugose, and the epipleuras in their 

 posterior portion broader and flatter. The sexual characters are quite the same, 

 the male tarsi being proportionately as small as in C. sugillatus. 



Siam, (Bangkok and Cliantaboun), Andaman Islands. 1054. 



1125. Cybister prolixus, n. sp. — Ovalis, elongatus, angustulus, supra olivaceo- 

 niger, subtus niger, pedibus anterioribus et intermediis rufo-variis, antennis rufis. 

 Long. 24, lat. 12 m.m. 



This species of which I have seen only a single individual is extremely closely 

 allied to C. sugillatus, but is more elongate, and has the male front tarsi larger, the 

 breadth of their third joint being about 2 m.m., while in C. sugillatus it is only 

 about H m.m. 



Ceylon. 1055. 



1126. Cybister convexus, n. sp. — Ovalis, sat latus, anterius parum angustatus, 

 convexus, supra olivaceo-niger, marginibus magis viridibus, subtus niger, antennis 

 rufis extrorsum fuscescentibus. Long. 29, lat. 16 m.m. 



This species is much larger than Cybister sugillatus, and of a different form, 

 being less narrowed in front, and so more regularly elliptical ; the front and middle 

 legs seem to be more nearly black in colour. The male front tarsi are slightly 

 more developed than in C sugillatus, and have the pubescent area at the base of 

 the undersurface distinctly larger ; the intermediate tarsi are wanting in 

 the only individual I have seen. It also a good deal resembles the African C. 

 binotatus (No. 1133), and is about the same size as the largest individuals thereof, 

 but is much more convex in form, and the male anterior tarsi are much smaller ; it is 

 probable that the species will prove intermediate between the Asiatic Cybister 

 sugillatus with its allies, and the African C. binotatus. 



East India. 1056. 



1127. Cybister posticus, Aube, Tro^TMs posticus, M. C. — Ovalis, latus, anterius 

 conspicue angustatus, supra parum convexus, nigro-olivaceus, pedibus anterioribus 

 et intermediis nigricantibus rufo-variis ; antennis rufis. Long. 30, lat. 16 m.m. 



I have seen of this species only a single individual ; it is the male from Dejean's 

 collection which served Aube for his description. It is closely allied to C. 

 sugillatus but is much larger and broader, the male front tarsi are larger, the 

 pubescent area at their base beneath being moderately large ; the line of sexual 



