90 BRITISH LEPIDOPTERA. 



Spiling.," p. 280 (1875); Kirby, "Eur. Butts, and Moths.," p. 72, pi. xvi., 

 figs. 4 a—b (1879); Buckl., "Larvae," &c, p. ir6, pi. xxvi., figs. 1 a — c 

 (1887); Ban-., " Lep. Brit.," ii., p. 55, pi. lii., figs. 2, 2a (1895); Tutt, "Brit. 

 Moths," p. 31 (1896). Afetopsilus, Dune, " Brit. Moths," p. 163 (1836); Kirbv, 

 "Cat.," p. 660 (1892); "Handbook," &c, iv., p. 26 (1897); Staud., "Cat.," 

 3rd ed., p. 104 (1901). Pergesa, Walk., "Cat. Lep. Het.," viii., p. 149(1856); 

 Maassen, " Stett. Ent. Zeit.," xxix., p. 437 (1868). 



This genus was diagnosed (Verz., p. 135) by Hiibner, about 

 1822, as follows : — 



Both pairs of wings exteriorly with dentate bands ; hindwings shaded with 

 yellow and black — Theretra equestris, Fab., T. nechus, Cram., T. porcelhis, Linn., 

 T. tersa, Fab. 



It will be observed that the original genus Theretra is 

 hopelessly heterotypical, but Stephens fixed the type as porcellus. 

 In his appendix to vol. iv of the Illustrations, Stephens published 

 a list of the British lepidoptera contained in the Verzeichniss under 

 Hubner's genera and we find Theretra (porcellus) mentioned as one ol 

 the subdivisions into which Boisduval's Deilephila is broken, whilst 

 the same author again used Theretra for porcellus in the List of tJie 

 British Animals in the Collection of the British Museum, pt. v, in 

 1850. This renders nugatory Moore's later restriction (Lep. 

 Ceylon, ii., p. 22) in which he makes nessus the type of Hubner's 

 genus Theretra (see, antea, vol. hi., p. 351, footnote). Later 

 authors, Kirby, &c, who have considered porcellus as generically 

 separate from elpenor, have used the name Afetopsilus, Dune, of 

 which, however, Westwood, in 1840, fixed the type as elpenor (thus 

 making it synonymous with Eumorpha), for the former species. 

 Metopsilus, Dune, is also not only a heterotypical genus, but com- 

 prises genera belonging to widely different Eumorphid (Chcerocampid) 

 tribes. The diagnosis reads : — 



The antennas are but slightly clavate, the anterior wings very acute at the 

 apex, with a slight sinuosity or emargination on the hinder margin, just below 

 the tip, which gives them a somewhat falcate shape ; the inner margin likewise 

 deeply emarginate behind the middle. The larvae offer several very distinctive 

 marks, particularly that of having the anterior segments very much attenuated, 

 and capable of being drawn within each other ; a peculiarity which has caused 

 them, as was formerly noticed, to be named " Chenilles cochonues " by French 

 naturalists, because the head and neck bear some resemblance to a pig's snout. 

 These caterpillars are not distinguished by great brilliancy or variety of colours, 

 being chiefly brown and green, with a white lateral line extending from the 

 anal horn to the third or fourth segment, and they have invariably two or three 

 large eye-like spots on each side, either of the second, third, fourth or fifth seg- 

 ments. The caudal horn is short, very slightly bent, sometimes almost obsolete. 

 The chrysalis is enclosed in a loose cocoon, formed of leaves, and is never 

 buried beneath the soil. The perfect insects are very beautifully coloured, anil 

 it is observable that the abdomen is always longitudinally or obliquely striped, an 

 arrangement different from that which obtains in the two preceding genera, 

 which have that part of the body ornamented with transverse bands, sometimes 

 of different colours. Viewed in relation to the form of the larvae as well as to 

 the appearance of the perfect insects, the species which we have placet! together, 

 under the above name, form a very natural group - nerii, eelerio, elpenor, 

 porcellus (Duncan, Naturalist's Library, xxx., pp., 154-155). 



The genus Theretra, according to Staudinger, contains three 

 Palaearctic species — porcellus, L., syriaca, Ld., mongoliana, Butl. This 

 grouping is utterly impossible. The larval structure of syriaca 

 certainly excludes this species from the tribe EtimorpJiidi (see 

 anted, p. 37, footnote). Weismann describes the larva (Studies 

 in the Theory of Descent, p. 191) as: "Green, having the short 



