SERICODERUS. 117 
SERICODERINA. 
SERICODERUS. 
Sericoderus, Stephens, Ill. Brit. Ent. Mand. ii. p. 188 (1829). 
Body oval, often attenuated posteriorly, thickly clothed with sericeous pubescence. Head small, wholly con- 
cealed by the thorax. Thorax rather large, the anterior margin entire ; hinder angles very much produced, 
embracing the shoulders of the elytra. Scutellwm large, rounded at the apex. lytra slightly truncate. 
Abdomen often much exposed. Antenne geniculate, 11-jointed—1 very long, much recurved, 2 about half 
as long as 1, incrassate, 3 and 4 very minute, 5 rather larger than 4, 6 very minute, 7 and 8 much larger, 
nearly equal to each other, 9-11 forming a subfoliate club. (This description, in which the relative size 
of the joints is taken from S. latus, will not equally apply to other species.) Palpi: mawillary large, 
4-jointed—l1 very small, 2 very large, turgidly incrassate, pyriform, truncate at the apex, 3 small, oblong, 
4 rather longer than 3, obtusely conical; labial moderate, 3-jointed—1 very small, 2 large, widest at the 
apex, the apex obliquely truncate, 3 short, transverse, with the apex rounded at the sides and faintly 
emarginate in the middle. Mentum large, subquadrate, widest at the base, the basal angles much rounded. 
Labium short and broad, rounded anteriorly, produced between the palpi, and bifid at the apex. Lingua 
broad, transverse, extending beyond the outer sides of the palpi. Zabrum small, transverse, faintly 
emarginate in front, furnished anteriorly with a few long sete. Mandibles small, rather narrow, armed 
at the apex with several sharp teeth. Maazlle unilobed; lobe long and slender, armed at the apex with 
long and very sharp teeth. Prosternwm very small, elevated between the coxe and produced and dilated 
beyond them; episterna very minute ; epimera moderate, enclosing the coxal cavities ; coxal cavities oval. 
Mesosternum rather short ; episterna large and broad; epimera large, not extending to the coxal cavities ; 
coxal cavities rather small, moderately distant. Metasternwm moderate, transverse, not extending to the 
sides of the body, the hinder margin between the coxe nearly straight; episterna as long as the meta- 
sternum ; epimera rather large, extending slightly beyond the metasternum ; coxal cavities long and narrow, 
reaching to the sides of the body, rather remote from each other. Venter composed of six segments—1 very 
long, as long as the metasternum, 2—6 nearly equal to each other in length, the apical segment sometimes 
elongate. Legs rather long and slender: anterior with the trochanters very small ; femora moderate ; tibie 
slender ; tarsi long and slender, 4-jointed—1-—3 almost equal, simple, 4 longer than the others; claws 
very slender, faintly curved; intermediate much longer than the anterior, in other respects similar ; 
posterior similar to the intermediate, but rather longer. Cova: anterior rather prominent, nearly con- 
tingent; intermediate moderately distant ; posterior rather remote, long and narrow. 
Sericoderus is easily known by the long and very acute posterior angles of the thorax, 
which, as in many of the Trichopterygide, embrace the shoulders of the elytra; and also 
by the silky pubescence, which usually covers the whole upper surface. But the species 
are difficult to distinguish from each other, as their chief diagnostic characters consist 
in the relative proportions of the joints of the antennee, and in the general outline and 
size of the body. The former of these characters can only be discovered by the tedious 
process of extending the antenne; and the latter is of its very nature comparative, and 
by no means obvious, when only a single species can be examined. 
Six species of this widely distributed genus have been described. 
1. Sericoderus latus, sp. n. 
Suboblongus, valde convexus, nitidus, obscure ferrugineus, pronoto dilutiore, pilis aureis sat dense vestitus ; 
pronoto breyi, antice sat attenuato, haud semicirculari, ad basin latissimo, flavescente, nitido, indistincte 
punctato, margine anteriore leviter reflexa, margine basali profunde sinuata angulis acutis valde productis ; 
elytris postice sat attenuatis, quam pronotum sesqui-longioribus, haud latioribus, ad humeros latissimis, 
