86 HYDROPHILID 2. 
fact that the tibie are not ciliate, and that the elytra are subacute at apex. I find, 
however, on examination of the insect I here describe as Limnocharis sinuatus, that the 
abdominal structure is essentially the same as that of Limnebius: viz. there are six true 
ventral plates, with a seventh more or less free and exposed; there appears to be no 
apical sete; but on pressing the elytra, so as to make them gape, the presence of a 
minute apical tuft is revealed. The eighth segment alluded to by Dr. Horn will, I expect, 
prove to be some part of another internal segment extruded in his specimen (which was 
unique). In some, if not in all, of the European Limnebii there is no ciliation of the 
legs, these being more or less distinctly spinulose. ‘The generic distinction of Limno- 
charis appears to me therefore to rest at present on the form of the apices of the elytra: 
and here the difference is conspicuous; the European Limnebii invariably have the 
extremities of the wing-cases truncate, exposing the apex of the hind body, while in 
Limnocharis the same parts are prolonged and acuminate. 
Limnocharis,.as will have been gathered from the above remarks, consists of a single 
minute Californian insect, probably very closely allied to the Guatemalan species, whose 
discovery we owe to Mr. Champion. I have no doubt that the two are at any rate 
congeneric, although the remarks I have made as to the discrepancy existing between 
the number of ventral segments as described by Horn and that seen by me in L. sinuatus 
might suggest the contrary. 
1. Limnocharis sinuatus. 
Ovalis, subdepressus, niger, sat nitidus, fere impunctatus, tenuissime pubescens; antennis, palpis pedibusque 
rufis, elytris ad apicem sinuatis et acuminatis. 
5 4: 
Long. 3 lin. 
Hab. Guatemata, San Joaquin in Vera Paz (Champion). 
This minute insect agrees with Dr. Horn’s description of L. piceus, except that L. sinuatus 
appears to be less punctulate, and that the very observant American entomologist says 
nothing as to the elytra being sinuate just before the apex. The unique individual of 
L. sinuatus before me is, I think, a male: it has the middle of the metasternum deli- 
cately pubescent on each side; the sixth ventral plate is very short, and, owing to its 
arcuation, appears emarginate behind; and the following exposed segment is evidently 
very mobile and capable of being withdrawn within, as well as extruded from, the 
preceding segments. The legs are quite simple. 
CHATARTHRIA. 
Chetarthria, Stephens, Ill. Brit. Ent. v. p. 401 (1832). 
Cyllidium, Er. Kaf. Mark, p. 212 (1837). 
Chetarthria is a very distinct genus of five or six species of minute beetles, one of 
these being European and another (doubtfully distinct, however,) Canarian, the other 
two or three being North-American. They are but little-known insects of very retiring 
habits; and their specific characters, so far as yet made out, are of the feeblest nature. 
