aquatic Coleoptera from Ceylon. 359 



rigid tarsi, much thicker at the base than at the apex. 

 The position should be between Oosternum and Perato- 

 gonus, to which latter peculiar genus it makes a con- 

 siderable approach. 



Armostiis optatus, sp. nov. 

 Eotundato-ovalis, convexus, rufiis, supra piceus, palpis anten- 

 narumque basi flavis ; fortiter piinctatus, elytris profunde striato- 

 punctatis, interstitiis convexis. Long. If mm. 



Head finely margined in front, closely and rather coarsely punc- 

 tured. Thorax rather coarsely and closely punctured at the sides, 

 more sparingly on the disc. Elytra with very deep striae, which 

 bear rather large punctures, the interstices are broad in front, and 

 become narrower and more elevated behind ; there is no pube- 

 scence ; the apex is flavescent. The under surface is finely 

 unctate and dull, except the remarkable mesosternal and meta- 

 sternal elevations. 



Dikoya, in December, 1881. Two specimens. 



