116 MISCELLANEOUS FOREST INSECTS.

angle. As stated by Reitter, later by Casey, and as is easily seen, they are produced and in some species as strongly as in any true Lyctus. Reitter in his synopsis states that in Trogoxyilon the sides of the head are provided with three hooklike teeth, that the pronotum has all its angles sharp, and that the elytra are without rows of punctures or hairs, but that these are irregularly disposed. As a matter of fact, LYctus (Trogoxylon) imnpressus Comolli does have the three elevations mentioned, but in all the species so far recognized in the United States not only the tooth over the eye is obsolete, but the posterior angles and margin of the epistoma are closely joined to the angles of the front, so that the epistoma is but slightly depressed below the level of the front, and the two elevations seen in many species of Lyctus are not traceable-a character also observable in L. (Xylotrogus) politus n. sp. The shape of the pronotum is of little value; in L. brunneus Stephens all the angles are acute. The elytral punctures in L. (Trogoxylon) californicus Casey are decidedly striate and there is a tendency to the same thing in L. curtulus Casey.
 The first visible ventral segment in most species which would fall in Trogoxylon is as long as the second and third combined, but in others it is not longer than the second and one-half of the third.
 Xylotrogus has long since been shown by Wollaston (1854) and other writers to be syfionymous with Lyctus, and Trogox'lon must also be so considered, though it might well be regarded as representing a well-marked subgenus.
 The species of the family Lyctide are very variable, especially in size. Well-developed individuals are frequently four or five times larger than others, the difference in size perhaps dependinglargely on food supply; for the offspring of those individuals which have bred in the same piece of wood for four, five, or six generations are very much smaller and quite different in some of the structural details from the first individuals reared. Accompanying the d(lecrease in size are found such changes as in the shape and punctation of the pronotum and the punctation and pubescence of the elytra. As a result, one must allow for much variation within the limits of the species, and characters which might be of specific importance in groups more constant in character can only be held to be individual.
 SYNOPSIS OF SPECIES OF THE GENUS LYCTUS.
 Elytral pubescence confused over the entire surface or sometimes in single rows,
 never in double series separated by wide intervals; apical angles of the prothorax usually dec(i(Ied(ly prominent if nott, at least suhprominent and the sides of pronotum decidedlyy convergent posteriorly.......... Division I, pages 117-119.
 Elytral iubescence always arranged in distinct series, the series at the sides at least
 4separate(d by a double row of fine, deep punctures or a single row of large, shallow, circular puncture ............. ..................Division 11, pages 119-120.