PROCEKDINGS Ol' SOCIETIES. 71 



cea?." The author desired to call attention to the want of syste- 

 matic arrangement which charactei'ises this favorite branch of 

 microscopical investigation, and to the necessity of a thorough 

 revision of the entire classification of tlie natural order. The 

 author presented to the Section two slides to illustrate his argu- 

 ments. The predominant form of frustules was first named by 

 Dr. Brebisson Cocconeis Icevis. In 1857 it Avas published by Mr. 

 lloper (j\I. I. vol. vi, p. 22) under the i)rovisional name Coscino- 

 discKs ? ovalia ; but in consequence of finding on the valves eight 

 to twelve submarginal obtuse processes with tumid bases, quite 

 distinct from the spines or teeth Avhicli occur in the Coscinodis- 

 ceae, the author considers this species must be placed in the genus 

 Eupodiscus, and may fitly be called Eupodiscus Icevis. The 

 specimens were obtained at Llandudno, in ripples in the sand 

 below mid- water ; and the paper concludes with a description of 

 some peculiarities connected with their sudden disappearance. 



Mr. John "Watson read a paper " On certain Scales of some 

 Diurnal Lepidoptera," in which he recommends a new and careful 

 study of this subject. In some genera peculiar scales, called 

 plumules, have long been known ; but examination with the 

 binocular microscope shows that they are not flat like the 

 ordinary scales, but cylindrical and holloA^-. They have been 

 found only in certain genera (named in the paper) at present, and 

 on the males alone : they possess generic resemblances and specific 

 differences, each species displaying its own distinguishing variety. 

 One of great beauty and novelty, found only on two African 

 butterflies, Pier is acjatldna and Pier is cliloris, was described, and 

 some very fine drawings of it, by Mr. Joseph Sidebotham, were 

 exhibited, and also other figures by him of about one hundred 

 species never figured before. The names and habitats of the 

 insects were given, and the author pointed out the value of these 

 scales for the assistance of the scientific entomologist in arranging 

 genera and species ; he then entei'cd into the question of their proba- 

 ble use as air vessels in the economy of the insects possessing them. 



The Chairman remarked that the scales of the Lepidoptera may 

 prove as valuable in detei*mining species as the scales of fishes. 



Mr. Sidebotham alluded to the value of the binocular micro-' 

 scope in defining the cylindrical form of the plumules, and 

 described the mode of finding them in sitic, by breaking the wing. 



Mr. AV"atson stated that some of Mr. Sidebotham's excellent 

 drawings were taken under the eighth objective, magnifying 750 

 diameters. Mr. "Watson further said that he had examined the 

 wings of 400 specimens of the Papilionidae, but had not discovered 

 any plumules in that genera : he also alluded to several so-called 

 species from South America, of which no male.s have yet been 

 found, others of which no females have yet been discovered, and 

 suggested the possibility of some of these being male and female 

 of tlie same species ; to ascertain which, careful examination of 

 the scales might be useful. 



Mr. AVatson exhibited a number of mounted specimens of the 

 plumules, and four cases of the Lepidoptei'a from whose wings 



