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



of the body. On the head there is a series on the 

 clypeus commencing on each side in front of the eye 

 and extending forwards, till near the front of the clypeus 

 it changes its direction by a curve, extending backwards, 

 and converging with its fellow of the other side towards 

 the mesial line of the back of the clypeus ; besides this 

 looped series there is a patch of punctures on the inner 

 margin of the eye ; on the thorax there is a lateral line 

 of punctures placed at a little distance from the side 

 about the middle of the length, and there is also an 

 anterior series consisting of two or three punctures 

 placed near the front of the thorax behind the eye on 

 each side. I have not made so much use, as I think I 

 might have done with advantage, of these systematic 

 punctures, and content myself with pointing them out 

 and recommending that attention should be paid to them 

 by future students. 



As regards the validity of the genus Tropisternus, I 

 must say that though it has not been admitted by some 

 of our best entomologists, it appears to me incontestable. 

 It was established by Solier in the ' Annales de la Societe 

 entomologique de France,' 1834, p. 308, by a dismember- 

 ment from Hydrophilus, in which its species had before 

 been included ; it differs from Hyd/rophilus by the different 

 proportions of the articulations of the maxillary palpi, 

 the penultimate joint of which is shorter than the ter- 

 minal one, while in Hydrophilus the contrary proportion 

 prevails ; the ventral segments in Tropisternus are 

 entirely pubescent, while in Hydrophilus they always 

 have a large glabrous area. There are also other minor 

 differences, of which an important one is the size of the 

 individuals : the largest Tropisternus only attains about 

 15 mm. of length, while the smallest Hydrophilvs has 

 about 25 mm., and the largest attains about 45 mm. 

 I think it is clear that we have here an aggregate quite 

 distinct from Hydrophilvs. 



Altogether I have discriminated thirty-five species, 

 but two of these form a distinct new genus on account 

 of the structure of the margins of the wing-cases ; the 

 other thirty-three species are arranged in ten groups, the 

 ten groups forming two very distinct sections. In the 

 Munich Catalogue of Coleoptera thirty-two species are 

 recorded under the genus ; of these some half-dozen are 

 mere synonyms ; one must be rejected as not belonging 

 to the genus ; and about half a dozen others cannot be 



