HELOPELTIS.—DERALLUS, 17 
HELOPELTIS. 
Helopeltis, Horn, Trans. Am, Phil. Soc. xiii. p. 137 (1873). 
This genus was established by Dr. Horn for a peculiar species having the labrum 
concealed under the clypeus, and this latter projecting laterally in front of the eyes to 
a greater extent than is usual in Helochares. But to the characters pointed out by Dr. 
Horn another, of much greater importance, must be added, viz. that the anterior coxal 
cavities are closed behind by the junction of the epimera with the prosternal process. 
This character isolates the insect from all the other Hydrobiini, although in other 
respects it is approached by various species of Helochares. 
1. Helopeltis larvalis. (Tab. II. fig. 15.) 
Helopeltis larvalis, Horn, loc. cit. p. 1377. 
Hab. Norta America, Louisiana 1.—MeExico, Sonora!; GuaTEMALA, Paso Antonio 
400 feet (Champion).—Cvusa 1. 
Only three individuals of this remarkable insect have been sent by Mr. Champion. 
It is highly probable that it possesses a peculiar mode of life. 
LACCOBIUS. 
Laccobius, Er. Kaf. Mark Brandenb. p. 202 (1837). 
This is a genus, of about twenty species, specially characteristic of the Mediterranean 
Region, but with two species in the Nearctic Region: of these two the one that is found 
in California extends its range to Mexico. 
1. Laccobius ellipticus. 
Laccobius ellipticus, Lec. Proc. Ac. Phil. p. 363° (1855). 
Hab. Norra America, California .—Mexico, Guanajuato (Dugés, coll. Sallé), Puebla 
(Sallé). 
DERALLUS. 
Corpus lateraliter compressum, subtus planum, superne longitudinaliter convexissimum. Tibi anteriores late, 
ad apicem longius oblique truncate, calcaribus distantibus, uno, parvo, ad angulum internum vel infe- 
riorem sito, altero, majore, ultra medium marginis sito. Oculi magni, parum prominuli. Abdomen ex 
segmentis ventralibus quinque compositum. Pedes intermedii et posteriores pro rematione valde modifi- 
cati; femoribus brevibus et latis ; tarsis compressis, apicem versus attenuatis; unguiculi omnes parvi. 
The form of the insect for which I have established this genus is most remarkable, 
and is only approximated by the Old-world genus Volvulus, where, however, the form is 
much more elongate, and comparatively less elevated and compressed. Derallus differs, 
too, from Volvulus in that it has five external abdominal segments, whereas in 
Volwulus the number is reduced to four; in Volvulus, too, the antenne appear to be 
