116 Mr. D. Sharp's revision of the species 



prothorax form a slightly irregular line ; the epipleural 

 margin is entirely without sculpture or spines ; the 

 swimming-legs are moderately stout, and their tibiae 

 possess a series of swimming-hairs parallel with their 

 upper edge ; the sternal spine is of moderate length and 

 not flattened ; the apical ventral segment bears a seti- 

 gerous tubercle near the hind margin. 



As regards the following species, or rather names of 

 supposed species, I can give no information beyond the 

 appended hints : — 



Tropisternus agilis, Cast., Hist. Nat., ii., p. 53. De- 

 scribed from St. Vincent. — I have not seen any speci- 

 mens from the island in question, but am inclined to 

 think from Castlenau's few words of description that this 

 may be a distinct species from any known to me. 



T. binotatus, Walker, Nat. Vancouver, ii., 1866, p. 318. 

 Vancouver's Island. — Leconte has identified this as 

 being H. limbalis, Lee. (cf. Ann. Nat. Hist., 4 ser., vi., 

 p. 400), so the name should pass into synonymy. 



T. blandus, Chev., Ann. Soc. Ent. Fr., 1863, p. 205. 

 Cuba. — The description of this species does not enable 

 me to form any opinion as to whether it is valid or the 

 name a synonym. 



Hydrophihis chalybcatvs, Curt., Trans. Linn. Soc.,xix., 

 p. 442. Brazil. — This is, I think, a mere synonym of 

 T. chalybeus, Cast. 



Tropisternus Icevigatus, Boh., Eugen. Besa, p. 22. Bio 

 de Janeiro. — I think this will prove to be a species un- 

 known to me, unless it be a variety of T. oualis, Cast. 



Hydrophihis Icevis, Sturm, Cat., p. 64, pi. 2, f. 13. 

 Cayenne and Brazil. — I find it quite impossible to come 

 to any conclusion as to what species this refers to. 



H. lepidus, Brulle, Voy. d'Orb., p. 57, pi. 4, f. 4. Entre 

 Bios. — This is clearly the same as T. scutellaris, Cast., 

 and, as I believe, though of this I am not quite sure, 

 that the latter name has priority, I have adopted it. 



H. limbalis, Lee, Proc. Ac. Phil., 1855, p. 367. — Being 

 unable to find any specific difference between North 

 American and South American individuals, I consider 

 this to be a synonym of H. dursalis, Brulle. 



