7-/130 
307 . 
b\ 
HYDR/ENA TESTACEA. 
Order Coleoptera. Fam. Helophoridae Leach . 
Type of the Genus, Hydrsena riparia Kug. 
Hydrjena Kug., Germ,., Sam., Steph. — Elophorus Gyll. — Hydrophi- 
lus Mar. 
Antennae inserted close to and before the eyes, not longer than 
the head and concealed beneath it, curved, 8?-jointed, basal joint 
very long, 2nd not so long, 3rd short, very much and acutely 
produced on the inside, the remainder more robust submoniliform 
and pubescent, the terminal joint the largest (6). 
Labrum horny large transverse and bilobed (1). 
Mandibles undiscovered. 
Maxillae small, furnished at the apex with an articulated ovate 
lobe and a ciliated one internally. Palpi as long as the thorax, 
4-jointed, basal joint minute, 2nd very long bent arid clavate, 
3rd very much shorter, subclavate, 4th twice as long, more robust 
and fusiform (3). 
Mentum rather large and subquadrate, dilated at the base, the 
anterior margin angulated ciliated and acuminated in the 
centre (4) . Labium and Palpi undiscovered. 
Head oblong dilated at the base where the Eyes are situated, touching 
the Thorax which is subquadrate, the sides being slightly convex and 
angulated. Scutellum minute. Elytra broader than the thorax more 
or less oval. Wings twice as long as the body and ciliated. Thighs 
incrassated at the middle. Tibiae simple. Tarsi rather long, 4 an- 
terior 5- jointed , 1st and 2nd joints very short, 3rd and 4th a little 
longer, 5th very long (5) ; posterior pair 4-jointed, basal joint ob- 
scure, 2nd short , 3rd long, 4th very long (5 f). Claws bent and 
acute. 
Testacea Curtiss Guide, Genus 108. 3. 
Pale dirty ochreous, not shining. Head black, deeply and thickly 
punctured especially on the crown. Thorax brown, anterior and 
posterior margins ochreous, an impression down each side the 
whole surface variolous. Elytra much broader than the thorax 
and ovate, each having about 1 1 lines of large and deep punc- 
tures leaving a mere line of surface between them. Antennae, 
palpi and legs pale ochreous. 
In the Cabinets of Mr. Dale, Mr. Walker, and the Author. 
Most of the Water-beetles are remarkable for having long 
external palpi, but in none is this character so striking as in 
the little insects before us, in which they are triple the length 
of the antennae. 
Having been so fortunate as to double the number of Bri- 
tish species within the last twelve months, and 3 only of them 
being described in the works of this country, I shall subjoin 
their characters. 
