ZOOLOGY AND BOTANY^ MICROSCOPY, ETC. 227 



on the leaf, and does not migrate to the stem till a later period than in the 

 case of larvae feeding on smaller leaves, such as Salix. The paper ends in 

 a summary, in tabular form, of the evidence derived from the various 

 experiments. 



Tracheal Gills of Pupse of Simulidse.* — Dr. Vogler has had his atten- 

 tion directed to some pupae which he found on various water-plants in the 

 Ehine, which were remarkable for the trachea-like shining tubes which 

 were developed at the anterior end of the body; in the more common 

 species they were proportionately short and thick, and in the other very 

 long and fine. The anterior end of the body of these pupse is blunt, and 

 forms an almost circular surface, the centre of which is occupied by the 

 pronotum; in the space between it and the case there are two spindle- 

 shaped gill-tubes, which are so bent as together to form a circle ; at about the 

 middle of one of these basal tubes there are given off six almost cylindrical 

 and equally long tubes, while a true trachea provided with a distinct spiral 

 opens below. A stigmatic ring connects the short process of the basal tube 

 with the trachea ; the latter is so distinct as to seem to lie outside the 

 body ; it then suddenly bends inwards, and passes to a tracheal limb of 

 the body. 



The apparatus consists, therefore, of two similar — right and left — halves, 

 which are not in direct connection with one another ; each half consists of 

 blindly ending tubes which form a circularly closed cavity which is con- 

 nected with the body-trachesB by a short connecting tube. There is no 

 essential difference between the form with short and that with long tubes. 



The tubes are filled with air so long as they remain connected with the 

 animal, but when the case is abandoned they become filled with water, and 

 form a home for infusoria, &c. Each tube has a thin and apparently struc- 

 tureless chitinous investment, on which is a thin granular or dotted layer ; 

 but it is not certain whether the dots are the optical expression of pores. 



Wings of Diptera.f — Dr. E, Adolph has systematized the descriptive 

 terminology of the veins and folds in the wings of Diptera, and has endea- 

 voured to trace the derivation of the manifold forms from a typical plan. 

 His patient and elaborate work is illustrated by figures of about fifty 

 different wings in which the concave and convex veins and folds are clearly 

 represented by lines of different colour and construction. The memoir 

 will doubtless be of service in facilitating the labours of specialists in this 

 department of entomology. 



Life-history of Aphides.J — Dr. H. F. Kessler has followed the life- 

 history of several species of Aphis, including especially A.padi, A. euonymi, 

 A. viburni, A. mali, A. pyri, and A. sambuci. He has shown that the genus 

 Aphis contains forms which exhibit essentially the same history as that 

 demonstrated in some Tetraneura, Schizoneura, and Pemphigus species. 

 At the end of spring, as Lichtenstein noted, they leave the plant which 

 they originally infest, and return to it at the end of summer or in autumn. 

 They survive the winter as ova, and begin their activity with the com- 

 mencement of the vegetation in spring. The author questions the correct- 

 ness of the supposition that the Aphides as such survive the winter, along 

 with, or even without the presence of ova. In Aphis padi the following 

 three phases in the cycle are distinguished : — (1) The spring phase on 

 Frunus padus, including the ancestral form, with its immediate progeny, 



* MT. Schweizer. Entomol. Gesell., vii. (1886) pp. 277-82. 



t Nova Acta Leop.-Carol. Acad., xlvii. (1885) pp. 269-314 (4 pis.). 



X Ibid., pp. 117-140 (1 pi.). 



