180 H. C. FALL. 



LeConte in 1862 and Mulsant and Rey in 1864 treated this group 

 with scientific acumen, but both being ignorant of Thomson's work, 

 many of the generic names proposed by them are synonymous with 

 those of the Scandinavian author. Later European writers have 

 exhibited a marked conservatism in their estimates of the import- 

 ance of the genera and subgenera proposed, and in the recent cata- 

 logue of Heyden, Reitter and Weise, Dendrobium (Ccelostethus 

 Lee), Microbregma, Hadrobregmus, Nieobium and Sitodrepa are all 

 regarded as subgenera of Anobium. The genus as thus constituted 

 seems to me undesirably complex. The association in the same 

 genus, of Dendrobium with its widely separated coxfe, broad trun- 

 cate presternum, deeply excavate metasternum and connate ventral 

 segments, and Sitodrepa with its narrowly separated coxae, acumi- 

 nate presternum, unexcavated metasternum and free ventral seg- 

 ments, is quite incongruous. Both Dendrobium and Sitodrepa pos- 

 sess full generic value and the same should I think be said of Nieo- 

 bium. Hadrobregmus and Microbregma are indeed much more 

 closely related to the true Anobium and might reasonably be con- 

 sidered of subgeneric import, though in the present essay I have 

 chosen to separate them as distinct genera. As here limited the 

 genus Anobium differs from Hadrobregmus only in its very deep 

 abruptly formed metasternal cavity and contains but a single spe- 

 cies occurring in both Europe and America. This is the common 

 European Anobium striatum Oliv., frequent in the walls of houses 

 where its habit in common with certain other species, of tapping 

 with its mandibles, the surface on which it stands has earned for it 

 among the superstitious the name of the death tick or death watch. 

 The resemblance of this species to certain Hadrobregmi is very 

 striking; so much so indeed that LeConte, failing to observe the 

 deep metasternal cavity, described native specimens under the name 

 Hadrobregmus pumilus. 



of subsequent commentators. This is the principal laid down in the " Merton 

 Rules," the "A. O. U. Code," indorsed after nature deliberation by the Entomo- 

 logical Society of London and has been accepted by the great majority of mod- 

 ern naturalists. It appears to me to be eminently logical and just. The method 

 advocated of late in certain quarters of determining a genus by the first species 

 described therein is simple, definite and convenient, and while in no sense scien- 

 tific might with advantage be used in the future; it should never be made retro- 

 active, however, for obvious reasons. 



