ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 45 



that of north-western Europe. Three diverse components may he dis- 

 tinguished :— (a) a small Celtic group, chiefly in Scotland and western 

 Ireland ; (b) a large Siberian group, with proximate origin in the plain 

 of Central Europe, prevented from complete access into Ireland ; and 

 (c) a Teutonic (easter a extension) and Iberian (western extension) group, 

 unrepresented in Scotland. " If any of our Coleoptera can be termed 

 autochthonous, the northern or Celtic element can be the only one so 

 regarded ; and, while all the rest of the fauna seems to have been derived 

 from the south and east, this only may have had a northern origin and 

 be possibly pre-glacial." But our ignorance vastly exceeds our know- 

 ledge of the factors of the problem. 



Aphidology.* — N. Cholodkovsky continues his stxidies on Aphides, 

 which are illustrated by an excellent plate. He discusses Chermes funi- 

 tectus Dreyfus, some new or little known species of Lachnus, the male 

 of Stomaphis graaffii, the Schizoneurinfe living in coniferous trees, 

 Gallipterus giganteus sp. n. from Alnus glutinosa, Tetraneura ulmi De 

 Geer, and Phylloxera quercus Boyer occurring in Northern Eussia. 



Nerve-Cells of Dytiscus.f — Dr. C. Tiraboschi begins an account of 

 his observations on the nerve-cells of invertebrates with a classified 

 bibliography, noting, for instance, those researches which describe the 

 internal structure of the nerve-cell as — (a) granular, or (6) fibrillar, or 

 (c) reticular. In Dytiscus marginalis he has found three different forms 

 of cellular elements, connected by intermediate forms — («) nuclei 

 apparently free, (b) chromatic cells with a minimum of cytoplasm, and 

 (c) ganglionic cells. Further report may be reserved till we see what is 

 to follow. 



Ants from Pacific Islands.} — Prof. C. Emery discusses the For- 

 micidee taken by Schauinsland's expedition. They are few in number, 

 and belong to species already described. From the Island of Laysan a 

 form was received which is described as a sub-species of Ponera puncta- 

 tissima Rog. (sub-sp. schauinslandi). Winged females only were found, 

 and it is possible that the workers may display characters sufficiently 

 marked to justify the erection of a new species. 



Swiss Collembola.§ — Herr J. Carl gives a faunistic account of 72 

 species and 14 varieties, to which four other species and a variety re- 

 ported by Nicolet have to be added. But this is not to be regarded as a 

 complete list. The influence of altitude on distribution is particularly 

 noticed ; thus Orchesella rufescens forma principalis, which is very com- 

 mon in the mid land, becomes gradually scarcer as one ascends ; while 

 Orchesella villosa is distinctively an inhabitant of the high-lying regions. 

 The forms from higher altitudes tend to be darker and smaller. The 

 character of the vegetation has also a great influence on the collembolan 

 fauna. A noteworthy result is the resemblance between the Swiss 

 Collembola and those of Northern Europe. About 60 species are shared 

 with Scandinavia. In regard to Sminthurus pruinosus and Achorutes 

 schotti — two northern forms — it is noted that they are very abundant in 



* Zool. Anzeig., xxii. (1899) pp. 468-77 (1 pi.). 

 t Boll. Soc. Rom. Stud. Zool., viii. (1899) pp. 53-65. 

 X Zool. Jahrb. (Abt. Syst.), xii. (1899) pp. 438-40. 

 Rev. Suisse Zool., vi. (1899) pp. 275-362 (2 pis.). 



