386 Mr. J. Nietner on new Ceylon Coleoptera. 



The half of this central costa and the exterior margin form an 

 elevated border round either elytron. The first and second on 

 either side run towards the apex, but come to a stop (very abrupt 

 in most, but less so in some, specimens) before reaching it ; the 

 third, after having been interrupted near its base by the sub- 

 humeral cavity, runs on, but does not reach as far as the former; 

 the fourth does not leave the region of the shoulder ; the last on 

 either side is very prominent at the base, but soon forms an 

 abrupt declivity, and runs on as a low ridge to below the middle. 

 The back of all these costae is obtusely dentated. The interstices 

 are marked with large, shallow, transverse impressions. The 

 head of the insect is rather large and even. The mandibles are 

 furnished with an obtuse subapical tooth, the two lower thirds 

 are ciliated. The maxillae have the apex of the outer lobe exter- 

 nally enlarged, rounded-off, and furnished with three strong 

 teeth replaced by cilia on the inside; the inner lobe is conic, 

 and similarly provided with teeth and cilia, but much thinner 

 and finer. The maxillary palpi are robust, the last joint is in- 

 flated at the base. The antennal club is hairy, dark (whilst the 

 remaining joints are yellowish), conic, and somewhat securiform, 

 the sixth joint being inserted on one side of the seventh. The 

 legs are robust, the tibiae slightly curved, obliquely truncated at 

 the end, furnished with spines along the outside, and with distant 

 cilia along the inner. 



27. Hydrochus lacustris, N. 



H. elongatus, subdepressus, supra metallicus, iridescens, subtus 

 piceus, pedibus, antennis, palpis elytrorumque margine magis mi- 

 nusve brmineis, mento cyaneo. Long. corp. m. 1 lin., f. multo 

 major atque robustior. 



Palpi maxill. robusti art. ultimo elliptico leviter inflato. Mandi- 

 bulee apice bifidse. Antennarum clava dense pilosa. Thorax oblonge 

 quadratus, basin versus angustatus, basi medio productus, cum capita 

 profunda punctatus. Elytra ad humeros oblique truacata, apicem 

 versus sat fortiter angustata, profunde striato-punctata. Tibiae extus 

 spinulosaj. 



Specimina nonnulla in lacu Colomb. legi. 



The head is robust, broader than the thorax ; the eyes large 

 and prominent. 



The femora, the last joint of the maxillaiy palpi, the mandibles 

 and the tarsal joints are dark towards the apex. The last abdo- 

 minal segment of the female is furnished with a bifid hairy 

 appendage. 



