The family _Ptinidæ_ includes two groups, _Anobium_ and _Ptinus_, the first being generally known as the "death-watch," from the peculiar sound, like the tick of a watch, which is produced by striking against a hard substance with their tiny jaws. Superstitious persons have long considered this noise an omen of death, hence the name. Instead of an ill omen, this noise proves itself to be a love-call between the sexes, and may be imitated accurately enough to elicit a response. One of the best known of these beetles is called _Sitodrepa panicea_, generally known in Europe as _Anobium paniceum_. It is a cosmopolitan feeder, having a reputation in several different fields of activity, commercial and scientific as well as literary. To druggists it is known as "the worm," and their stock of ginger, rhubarb, Cayenne pepper, nux vomica, and belladonna root all appear to be equally to its liking, tin foil being no formidable barrier to its persistent search. Leather dealers have suffered from the destruction wrought by this little fellow to such an extent that whole cases of boots and shoes, carriage trimmings, etc., have been ruined. To this species belongs the insect found a few years ago at work in a volume of Dante's Divine Comedy, which had been sent to Cornell University library from Florence. The larvæ are about three to four millimetres in length, of a dirty-white color, head tinged with brown, and black mouth parts, with the abdomen strongly curved. The adult is a small, cylindrical, brown beetle from two to three millimetres in length, with head bent down and wing covers marked with fine punctate striæ. Professor Poey made extensive observations of an insect in Cuba which had destroyed about four thousand volumes. He called it _Anobium bibliothecarum_, and Schwartz thinks the injury reported by Herminier from Guadeloupe should be attributed to the same species. _Anobium striatum_ and _pertinax_ have long been known to injure books by their "gnawing and burrowing," not only in and through the bindings, but also entirely through the volumes. _Nicobium hirtum_, a native of southern Europe, where its larvæ have been found doing like injury, is only locally abundant, and for this reason has never been considered a serious library pest. Schwartz says, "In one way or another the insect has found its way to North America, but has always been regarded as a great rarity with us."