216 Proceedings of the Royal Physical Society. 



the small Spring-tail found near Edinburgh in March 1899, 

 and recorded in our paper above referred to under that name, 

 is a different insect ; and having failed to identify it with 

 any other known form, unless it be that recorded by Brook 

 (1884) also as A. maiiubrialis, we take this opportunity to 

 give a description of it under the new name of Achorutes 

 propinqiius. 



It may be well also to mention now the following changes 

 in the nomenclature used in our Edinburgh list (1899). 

 (1) Isotoma arhorea, Linn., has been shown (Agren, 1903) to 

 be a prior name for the insect we recorded as /. sensihilis, 

 TuUb.; and (2) Isotoma Besselsii, Pack., is an older name for 

 /. spitzbergenensis, Lubb. 



Order COLLEMBOLA. 



Family ENTOMOBRYIDJE. 



Isotoma sexoculata, Tullberg. 



[Plate IV. Figs. 1-4] 



Numerous examples of this Spring-tail were found by 

 Evans under stones below high-water mark on the shore of 

 the Firth of Forth at Dalmeny, about a mile east of South 

 Queensferry, Linlithgowshire, on 23rd March 1901. 



The marine station in which we found this insect is 

 remarkable, since in its other known localities — Sweden 

 (Tullberg, 1872), Hamburg (Schaffer, 1896), Bergen (Lie- 

 Pettersen, 1896), and Kiev (Scherbakow, 1898) — it does not 

 haunt the sea-shore. The species is recognisable by its 

 short feelers, legs, and spring, and by the presence of three 

 ocelli only on either side of the head, behind the narrow 

 crescentic post-antennal organ (Figs. 1, 2). The feet and 

 claws are simple (Fig. 3), while the spring (Fig. 4), evidently 

 borne on the fourth abdominal segment, has a slender, 

 elongate mucro with two teeth. From the descriptions given 

 by Tullberg and Schaffer, we gather that our specimens, 

 which are greyish white, are paler in colour than typical 

 Continental examples of the species. 



