82 THE AMERICAN NATURALIST. Vot. XXXII. 
tion of Redtenbacher! that any great progress was made. This 
paper, with its numerous illustrations drawn from nearly all 
orders of winged insects, is really the starting point in the 
actual solution of the problem. 
Unfortunately, however, Redtenbacher was misled by the 
erroneous theory of alternating convex and concave veins elabo- 
rated by Adolph.? The result was that, although Redtenbacher 
recognized the homologies of the main stems of the principal 
veins, he, in his efforts to apply this theory, was led into many 
serious errors. 
Then Spuler? followed, and, basing his conclusions on a 
study of the trachez that precede the wing-veins, worked out 
the type of the lepidopterous wings. Unfortunately, Spuler 
overlooked the trachea that precedes the first of the principal 
veins, and began his numbering with the second principal vein, 
which he designated as vein I. 
The next step in advance was made by the senior writer of 
the present series of articles. In a text-book of entomology * 
he worked out the homologies of the wing-veins in the Lepi- 
doptera, Diptera, and Hymenoptera. In the preface of that 
book he said: 
The principal features of the method of notation of wing-veins, 
proposed by Josef Redtenbacher, have been adopted. But as the 
writer’s views regarding the structure of the wings of primitive 
insects are very different from those of Redtenbacher, the nomencla- 
ture proposed in this book is to a great extent original. The chief 
point of difference arises from the belief by the present writer that 
veins IV and VI do not exist in the Lepidoptera, Diptera, and 
Hymenoptera; and that, in those orders where they do exist, they 
are secondary developments. 
But again, unfortunately, the work was not carried far 
enough. While the non-existence of the concave veins IV 
1 Josef Redtenbacher, Vergleichende Studien über das Fliigelgeader der 
Insecten. Ann. des. k. k. naturhist. Hofmuseums, Bd. i, 1886, pp. 153-232. 
2 G. Ernst Adolph, Ueber Insectenflügel, 1879. 
3 A Spuler, Zur Phylogenie und Ontogenie des Flügelgeäders der Schmetter- 
linge. Zeit. f. wiss. Zool., Bd. liii, 1892, pp. 597-646. 
* J. H.and A. B. Comstock, 4 Manual Jor the Study of Insects. Ithaca, N. Y., 
1895. 
