Mr. J. Nietner on new Ceylon Coleoptera. 387 



28. Hydrous rufiventris, N. 



H. ovatus, convexus, supra oleagino-niger, subtus obscure ferruginous, 

 pedibus dilute piceis, labro seneo, reliquis oris partibus cum clypeo 

 testaceis. Long. corp. 8 lin. 



Palpi maxill. articulis apicem versus abruptius incrassatis, art. 3** 

 quarto sesqui longiore. Antennae art. 7-8 fortiter perfoliatis, ultimo 

 acuminato. Caput antice utrinque punctulorum serie subsemicircu- 

 lari et ad oculorum marginem interiorem impressum. Thorax punc- 

 tulorum seriebus 4 lateralibus, 2 subapicalibus obliquis abbreviatis 

 signatus. Elytra subtiliter striato-punctata. Tarsi omnes unguibus 

 basi fortiter unidentatis. Carina prosternalis cultriformis. 



Specimen singulum f. nocte ad lumen cepi. 



As far as my resources allow me to ascertain_, a very anomalous 

 species, having the perfoliated antennae and toothed claws of a 

 Hydrophilus and the cultriform prosternal carina and the elytra 

 of a" Hydrous. I have placed it in the latter genus on account 

 of the sharp edge of the prosternal carina, in which the great 

 distinguishing character of this genus seems to lie, this part 

 being deeply grooved in Hydrophilus. 



The insect at once attracts attention by the reddish colour of 

 its abdomen. It is of a blackish olive-colour on the back, having, 

 however, the clypeus and the anterior margin of the labrum of a 

 yellowish brown, the latter being otherwise of a rather metallic 

 colour. The remaining parts of the mouth are more or less 

 yellowish. Joints 1-6 of the antennae are yellowish too, with 

 the exception of the second, which is dark; joints 7-9 are 

 blackish and pubescent. The legs are of a light pitch- colour. 

 The lower part of the head is impressed with two rather semi- 

 circular series of punctures, similar punctures occurring along 

 the internal margin of the eyes. The thorax is marked with six 

 series of them, and on the elytra they are arranged in lines. 

 The sternal carina is well developed, the prosternal part has a 

 sharp edge, whilst the mesosternal one is obtuse on the back, 

 and the metasternal part depressed and slightly grooved. 



29. Hydrous inconspicuits, N. 



H. praecedente minus convexus, supra oleagino-niger, subtus rufo- 

 piceus, ore testaceo. Long. corp. 4^ lin. 



Palpi maxill. art. 2^ et 4° subeylindricis, 3° apicem versus sensim 

 incrassato, sequente tertia parte longiore. Antennae art. 7-8 sub- 

 globosis, 9° magno, ovato. Caput, thorax et elytra ut in praecedente 

 sculpta et signata. 



In lacu Colomb. mens. Jun. non infrequenter cepi. 



This is in every respect a normal species. The prosternal 



25* 



