ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 37 



the edge armed with two blunt processes, the point of the central 

 mass projecting between them, and armed with chitin. (h) as (a) 

 but the point of the central mass prolonged to as great a length 

 as the cylinder itself, or greater. 7. Egyholia Vaillantina, A very 

 thick-walled cylinder, the central mass projecting by a small conical 

 process from its extremity. A form allied to this is exhibited by 

 an Australian moth, viz. a pointed cylinder, the central mass pro- 

 jecting from its side as a very small process. 8. Eecurvate juice- 

 borers. Eecurvate hooks, calculated to lacerate the tissues when the 

 proboscis is withdrawn from a soft vegetable mass into which it has 

 been plunged ; e. g. Ophideres, Achcea chamceleon, Egyholia Vaillantina, 

 Scoliopteryx lihatrix. 



Functions of Juice-borers. — The object of obtaining supplies of 

 juice is clearly that of the last form ; that of the simplest forms 

 must be sought in their origin from simple hairs, which must have 

 been originally organs of touch ; but, in spite of Fritz Miiller's view 

 as to the general prevalence of this latter function, they must be 

 considered, from their structure and position, to be truly and solely 

 instruments for extracting juices. The cases in which the structure 

 of these organs is known are too few at present to base classificatory 

 systems upon them, and in some cases they appear to be little adapted 

 for such a purpose, as, for example, the form with longitudinal ridges 

 (No. 3), which occurs in numerous European genera of each of the 

 three groups, JBomhyces, NoctucB, and Geometrce, besides some genera 

 of uncertain position. In the Micro-lepidoptera they have not been 

 examined. 



Internal structures of the halves of the proboscis. — The muscles 

 consist of a main longitudinal band passing from base to apex, and of 

 numerous small branches passing off obliquely from it, and attached 

 on the upper side ; the latter cause the tube to roll up by contracting 

 first near its apex, and then in succession towards the base. The 

 nerves are not known. A tracheal tube traverses each of the maxillae, 

 ending blindly at its apex. 



The closing of the two halves, in a species of Sphinx, is effected by 

 two different arrangements. The lower edges are joined by means 

 of a pair of teeth in each half (as seen in transverse section), which 

 interlock with those of the opposite half; on the upper side the 

 integrity of the tube is effected by fine hairs and spines in the 

 two halves, which cross and form a kind of joint. Similar arrange- 

 ments appear to occur in some other forms. The act of sucking 

 appears to be caused, not by exhaustion of air by means of the 

 tracheae, as would be the case if the method had an analogy with that 

 of higher animals, but by partial separation of the two halves of the 

 tube, causing attenuation of the enclosed air, and forming an imperfect 

 vacuum, which thus allows the pressure of the external air to act on 

 the juices of the flowers attacked by the insect. 



Post-embryonic Development of Diptera.*— H. Viallanes, noting 

 that of all insects the Muscidae exhibit the greatest differences between 



* Comptes Keudus, xciii. (1881) pp. 800 2, 



