BY R. J. TILLYARD. 173 



It will be seen that, in the Numerical Notation, the veins 

 numbered from 6 to 11 are falsely homologised in fore- and hind- 

 wings. The same fault is apparent in the 8taudinger-Schatz 

 Notation. The author believes that the true scientific spirit 

 will no longer tolerate false homologies in the interpretation of 

 \\ ing-venations, and the systems that perpetuate them must give 

 wav to a system of correct homologies. This alone would be 

 sufficient justification for the adoption of a new system. Jf we 

 add to this, that the system here ofi'ered has two other great 

 advantages, viz., («) that it brings the Lepidopterous venation 

 into line with that of all the primitive Orders to which the 

 Comstock-Needham System is readily applied, and (b) that, by 

 the u.se of the trigamma as a key, the veriest tyro can unlock 

 the secrets of the Lepidopterous wing with ease, while supposedly 

 aberrant forms like Castnia fall simply and readily into their 

 proper places, the case for the adoption of the new system 

 becomes irresistible. 



Believing that the question of jugum and frenulum is of less 

 importance than the actual wing-venational scheme, the author 

 proposes to subdivide the Order Lepidoptera into two primary 

 divisions. 



A. Lepidoptera Homoneura^ with venations of fore- and hind- 

 wings closely similar and of primitive design. (This includes 

 Micropterygithe and Hepialidce). 



B. Lepidoptera Beteroneura, with the venation of the hind- 

 wing reduced, and differing widely from that of the forewing. 

 (This includes all the rest). 



Explanation of jS'otatioii used in the Text-Jigures. 



All the main veins (C, Sc, R, M, Cu, and A) and their branches, 

 as named in the Table of Homologies on p. 172. In addition : — 



Closed cells (primary): dc, discoidal or radial cell; mc, median 

 cell. (Secondary) : L., the Lepidopterous " cell.'" 



Junctions or forkings of main veins : cuf., first forking of Cu; 

 cuj'., second forking of Cu (Cuj); mf., the thyridium, or median 

 forking; r/., first forking of R; rf ., second forking of R (Rs). 



The five primary Apical Forks : A/1 (between R._, and R^); 

 Af2 (between R, and R,); AfS (between M^ and M.); Af4 (be- 



