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Show 516 INSECTA. MoNOTOMA, Herbst.-Cerylon, Gyll. Or Monotoma properly so called, have a head of the same width as the thorax, and separated from it by a strangulation. The two first joints of the antennce. are stouter th~n the following ones, and almost equal-the first a httle larger. 1 he superior ex. tremity of the club, or button, seems to present vestiges of one or two joints. The head is triangular, an somewhat extended intoan obtuse snout. The body is elongated, aud the thorax longer than it is wide( 1 ). 3. The Xylophagi of the third division have eleven very dis· tinct joints in the antenn:e ; their pal pi are filiform, or thicker at the extremity in some, and smaller in others; all the joints of the tarsi are entire. We will begin with those in which the club of the antennre consists of but two joints. They form the genus LYCTUS. In some, the mandibles and first joint of the antennre are com· pletely exposed. The body is narrow, elongated and almost linear; the eyes are large and the thorax is elongated. LYoTus, Fab.(2) In Lyctus proper, the margin of the head covers the whole or greater part of the first joint of the antennce. The mandibles are not salient. In DroDESMA, Meg. Dej. The antennce are as long as the thorax, the body is a convex, ob· long oval, the thorax is almost semiorbicular, and the abdomen nearly oval(3). BrToMA, Herbst. Gyll.-Lyctus, Fab. Where the antennre are shorter than the thorax; the body is long, narrow, depressed, and almost a parallelopiped; the thorax is square(4). (1) Cerylon picipes, Gyllenhall. (2) See Lat,, and Gyllenhall. The genus Lyctus of Fabricius is a mixture. (3) Diodesma subterranea, Dej., Catal., p. 67. (4) See Lat., Gyllenhall. COLEOPTERA. 517 ln the other Xylophagi with antennre co~posed of eleven joints, the three or four last form the club, or the last is alone larger than the preceding ones. They at·e subdivided thus: · Sometimes the mandibles are covered or project but little, ~s in M YCETOPIIA.Gus, Fab. Here, the antennre, barc11y longer than the head, are inserted under the projecting margin of the head, and terminated abruptly by a triarticulated, perfoliate club. CoLYDIUM, Fab. Their body is linear, and the head very obtuse before; the thorax is as wide as the abdomen, and forms a square more or less long; the abdomen is elongated. The two first joints of the antennre are larger than the following ones, which, to the eighth inclusively, are very short and transversal( 1 ). There, the antennre are at least as long as the thorax. The body is oval, the thorax. transversal and widest posteriorly; the fhst and last joints of the tarsi are elongated, and the antennre terminate in a perfoliate club, either oval and commencing ncar the sixth or seventh joint, or abrupt, somewhat oval, and formed of the three last. They lire in mushrooms or under the bark of trees. MYCETOPHAGus, Fab.-Tritoma, Geoff. In Mycetophagus pt•oper, the club of the antennre commences at the sixth or seventh joint; the last is almost ovoid(2). TRIPHYLLus, Meg. Dej.-JJtlycetophagus, Gyll. Where the club of the antennre is shorter, abrupt, and formed by the three last joints only; the last one is almost globular(3). Those have an oblong body and the thorax narrower than the abdomen, at least posteriorly; the first joint of the tarsi is the length of the following one, or hardly longet·, and the antennre are terminated by a narrow elongated club, but slightly or not at all perfoliatc, formed by the three last joints. The (1) See Lat., Fab., Dej. (2) See Lat., Gener. Crust. et Insect., Ill, p. 9, first division of the Myceto· phagi; and Gyll., Insect. Suec., I, iii, 387, and IV, 630. (3) See Lat., Ibid., second division; Dej., Mycetophagi, and Gyllenh., Ibid., IV, 631. |