HYDROBIUS.—METACYMUS. 65 
an elongate sutural stria. Legs red, with the tibie and tarsi pale, the latter very slender. 
The prosternum is distinctly carinate along the middle, the anterior portion of the carina 
projecting so as to form a well-marked angle; the mesosternum bears a lamina which 
extends very far forwards, its anterior margin ascending in a curve to the front of the 
middle of the mesosternum. 
This minute beetle is allied to H. subcupreus, but is readily distinguished by the 
sparse punctuation of the upper surface and the extreme development of the meso- 
sternal lamina. 
3. Hydrobius debilis. 
Ovalis, posterius subattenuatus, parum convexus, nitidus niger ; prothoracis elytrorumque marginibus lateralibus, 
pedibus, antennarum basi palpisque testaceis, his articulo ultimo fusco; elytris crebre punctatis sed ad 
basin levigatis, stria suturali anterius desinente ; mesosterno tuberculo parum elevato. 
Long. 3-4 lin. 
Hab. Mexico, Toxpam (Sallé); Guatemata, San Gerénimo, Cahabon, San Joaquin, 
San Juan, Coatepeque 1300 feet, Pantaleon 1700 feet, Lanquin, Guatemala city, Paso 
Antonio (Champion) ; Panama, Volcan de Chiriqui, 2500 to 4000 feet (Champion). 
The individuals of this species are the smallest of the genus. The palpi are short 
and stout; the yellow colour forming the lateral margin of the thorax is more or less 
prolonged inwards along the anterior and basal margins; and the pale margin of the 
wing-case forms a very definite stripe, quite narrow at the base, but becoming gradually 
a little broader towards the apex. The punctuation of the wing-cases is peculiar, is 
not arranged in series, and is quite wanting about the base. The hind tarsi are elongate 
and extremely slender. The mesosternum bears in the middle in front a slight tubercular 
projection; the prosternum is without carina. I am not aware that this minute insect 
has any very near ally. It varies a good deal in size and colour and in sculpture of the 
upper surface, in a somewhat similar manner to what occurs in its European ally 
H. limbatus ; the most marked of the varieties has the colour of the wing-cases greatly 
diluted and their punctuation diminished, and the tubercular elevation on the meso- 
sternum almost absent. The numerous specimens found by Mr. Champion at Cahabon 
are all referable to this pallid variety ; but intermediate individuals connecting the variety 
with the larger and darker specimens are not wanting. 
METACYMUS. 
Generis Anacene affinis. Caput latum, ante oculos dilatatum; labrum fere occultum. Antenne perbreves, 
7-articulate. 
The unique example of the minute and obscure Palpicorn on which I base this genus 
is of very convex form, and, being somewhat compressed laterally, approaches a little in 
its form to Volvulus. ‘The head is very broad and short; and the clypeus is scarcely 
emarginate in front, and the labrum almost entirely concealed ; on each side the clypeus 
BIOL. CENTR.-AMER., Coleopt., Vol. I. Pt. 2, October 1882. KK 
