aquatic Coleoptera from Ceylon. 343 



to the suture. The hind angles of the thorax are prolonged back- 

 wards in a spiniform manner. 



Mr. Lewis obtained about a dozen examples of this 

 species in a rapid stream at Kitulgalle. 



Hydrovatus castanens. 



Hydrovatus castaneus, Motsch., Et. Ent., 1855, p. 82. 



Colombo. 



Hydrovatus fusculus. 



Hydrovatus fuscidus, Sharp, Dyt., No. 193, p. 326. 



Kandy and Colombo. 



Hydrovatus elevatus. 



Hydrovatus elevatus, Sharp, Dyt., No. 199, p. 328. 



Kitulgalle. Only one specimen was obtained ; it is a 

 variety of very small size. 



Hydrovatus sinister, sp. nov. 



Subrotimdatus, testaceus ; elytris fusco-testaceis, fortiter punc- 

 tatis, ad apicem profunde sinuatis. Long. 2i^ mm. 



Head broad and short, very indistinctly impressed on each side, 

 obscurely margined in front, very densely and finely reticulate. 

 Thorax rather sparingly and finely punctured, densel}- and finely 

 reticulate. Elytra rather coarsely and regularly punctate, shining, 

 very indistinctly reticulate ; the acumen at the extremity remark- 

 ably definite. Under surface shining, coxae coarsely punctate. 

 Prosternal process triangular, not sinuate at the sides. There is 

 only a very slight difference in the structure of the antennae of the 

 two sexes, but in the male they are distinctly a little longer, and 

 very slightly broader than they are in the female, and joints 4 — 7 

 of the antennae are just perceptibly broader. 



This species should be placed near H.fractus, Shp. ; 

 it is more sparingly punctate and more shining, and has 

 the acumen at the extremity of the elytra remarkably 

 definite and distinct. 



Colombo, in April. About a dozen specimens. 



