On Aquatic Carnivorous Coleoptcra or Dytiscidoe. 339 



226. Hyphydrus obniger, Chev., M.C. — Ovalis, nitidus, convexus, sat angustus 

 et elongatus, piceus, capite thoraceque dilutioribus, antennis pedibusque rufis ; 

 prothorace crebre, irregulariter, subtiliter punctato ; elytris sat sparsim et subtiliter 

 punctatis. Long. 4i m.m., lat. 2| m.m. 



This species is narrower than P. punctatus, and readily distinguished by the 

 much finer punctuation of the elytra ; this towards the sides is a good deal closer 

 and coarser than it is on their sutural portion. The species is very closely allied 

 to P. obesus, but is more elongate, the punctuation of the thorax is coarser, while 

 that of the elytra is rather finer (especially on the sutural portion), and less close 

 and distinct. 



Cuba. 50. 



227. Pachydrus obesus, n. sp. — Ovalis, nitidus, convexus, sat latus, piceus, capite 

 thoraceque dilutioribus, antennis jDedibusque rufis ; prothorace irregulariter, sub- 

 tiliter, sparsim punctato; elytris crebre vix fortiter punctatis. Long. 4, lat. 

 2f m.m. 



The surface of the thorax in this species is but little uneven, but the punctures 

 are scattered in an irregular manner, and are quite fine, being not at all coarser than 

 those of the head. Tlie punctures of the elytra are rather small, but rather deep and 

 distinct. The species is slightly narrower in its form than P. punctatus, but is 

 very readily distinguished therefrom by its punctuation. 



Venezuela, (Cumana). 51. 



228. Pachydrus brevis, n. sp. — Ovalis, sat nitidus, latus, piceus, capite thoraceque 

 dilutioribus, antennis pedibusque rufis ; prothorace superficie vix intequali, sparsim 

 punctato; elj'tris crebre sat fortiter punctatis. Long. 4, lat. 2f m.m. 



This species is intermediate in form and sculpture between Pachydrus cribratus and 

 Hyphydrus obniger, (No. 226). It is rather more elongate than Pachydrus cribratus, 

 and is readily distinguished by the much less dense sculpture of the elytra ; it is a 

 good deal less elongate than Hyphydrus obniger, and has the sculpture of the 

 upper surface much coarser, deeper and closer ; it differs from Pachydrus cribratus 

 very slightly, except in the sculpture, the distinction in this respect being however 

 very conspicuous. 



Porto Eico. Antigua. 158. 



TRANS. EOT. DUB. SOC, N.S., VOL. II. 2 T 



