250 Proceedings of the Royal Physical Society. 



shows, however, a small but distinct tooth (Fig. 26), and the 

 mucro has in most cases four teeth (Fig. 27), agreeing exactly 

 in form with that of /. denticulata, Schaffer (13). Dr Schaffer 

 also kindly examined some of our specimens, and at first 

 referred them to the latter species. He has since informed 

 us (in lit. 15/1/99) that he has detected differences, but a 

 comparison of the Edinburgh insects with Hamburg speci- 

 mens, courteously communicated by him, leads us unhesi- 

 tatingly to agree with his earlier opinion. In /. denticulata 

 three tenent hairs are said to be present on all the feet, but, 

 as Dr Schaffer has himself informed us, this character is not 

 constant. As some of our specimens (like one of those from 

 Hamburg) show the three-toothed mucro of typical /. sensibilis 

 (the small ventral tooth of Fig. 27 being absent), we have no 

 hesitation in referring the whole of them to that species, and 

 considering the form of the mucro not to be a constant specific 

 character. We believe, therefore, that neither /. denticulata, 

 Schaffer, nor /. duhia, Keuter (11) — the latter founded on a 

 single individual— can be specifically distinguished from /. 

 sensibilis. 



This small Spring-tail is widely dispersed in the district, 

 and where found it is usually plentiful. Its favourite habitat 

 is under damp bark on fallen trees that are far advanced in 

 decay. A ready way of finding it is to beat pieces of the 

 bark over a sheet of white paper. When alive, the usual 

 colour is dark purple with green reflections. 



/. sensibilis was described by Tullberg (17) from Novaya 

 Zemlya, and it has been recorded from Finland, Sweden, 

 Norway (whence we have a typical example kindly sent us 

 by Mr Lie-Pettersen), and Germany; it also occurs in 

 Ireland. That it should have remained so long unnoticed 

 in this country is somewhat singular. 



Local data. — Abercorn (Linlithgow), 1st Oct. 1896, oue specimen; Vogrie 

 Glen (Midlothian), 27th Feb. 1897, abundant under bark on old tree stump; 

 CuUalo (Fife), 3rd April, plentiful under bark on prostrate and decayed fir ; 

 Dollar, April, a few; Bridge of Allan (S.W. Perth), Feb., a few under bark 

 lying on a wet bank ; Hallyards, near Kirkliston, March, abundant in usual 

 situation; Dalhousie, March, several; Swanston Wood, May and Nov., 

 common ; Dalmeny Park, Dec. ; near Kosslyn, March, common ; Kirknewton, 

 May, a good many, some dark greenish-grey. 



