﻿254 [ A P"i. 



2. Helochares, Mulsant. 



Of an oblong-oval form ; mesosternum simpl e ; tibiae feebly spinulose ; 

 maxillary palpi very long, the third joint not so long as the second, and the fourth 

 not so long as the third, but more than half the length of the second. Labial palpi 

 short, the third joint not quite so long as the second. 



Two British species ; lividus and punctatus. 



This genus, established some years ago by Mulsant, has not been 

 generally accepted by entomologists, and is usually considered a sub- 

 division of Philhydrus : from this, however, it is distinguished readily, 

 by its simple mesosternum and its longer maxillary, in conjunction with 

 its shorter labial, palpi ; this last character, a very striking one, seems 

 to have entirely escaped attention up to this time. The species of 

 Helochares are flatter than the PhilJiydri, and rather narrower to the 

 front ; this and the more developed maxillary palpi give them a facies 

 of their own, easily recognised after it has been once seized.* 



3. Philhydrus, Solier. 



Of an oblong-oval form ; mesosternum carinated, tibia? feebly spinulose. 

 Maxillary palpi long, second joint considerably longer than the third, and the 

 third than the fourth ; the fourth not quite half so long as the second. Labial 

 palpi long and slender. 



We have six indigenous species ; testaceus, maritimus, melanoce- 

 phalus, nigricans, ovalis and marginellus. 



Obs. — The figures are drawn from dissections of P. melanocephalus : 

 in P. maritimus, the labial palpi, though similar in structure, are rather 

 shorter, and not quite so slender, and the mentum is even more rounded 

 in the middle. 



4. En ochres, Thomson. 



Of an oval, convex form ; mesosternum carinated, tibiae feebly spinulose. 

 Maxillary palpi rather long, third and fourth joints of nearly equal lengths ; second 

 longer than either of them. Labial palpi rather short. 



The single species of this genus, JE. iicolor, Payk., has hitherto 

 been placed in the genus Hydrobius, from which it differs in numerous 

 important characters. It is distinguished from Philhydrus, however, 

 only by the differences of the palpi ; and, as it has in every respect 

 the facies of that genus, if Enochrus be not adopted, it must be con- 

 sidered as a section of Philhydrus. 



* In making the above engraved drawings from Dr. Sharp's dissections, I have, moreover, observed 

 that the mentum in Helochares lividus is of a very different structure to that of Philhydrus, having 

 an acute triangular notch in the middle of its anterior margin. Dr. Sharp (to whom I pointed this out, 

 and whose observation it had escaped through the medium in which his dissections were mounted not 

 having dried up enough for minute investigation) has verified this by further observations. — E. C. R. 



