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APPENDIX 
and for the unusual size of the marginal nervure (Fig. 7, M), which is 
indeed much larger than the costal and subcostal nervures (Fig. 7 c and sc). 
The cavity formed by the costal fold is bounded and closed beneath by 
very numerous scales arising along the straight line which separates the 
folded margin from the rest of the wing, and above by the margin of the 
fold. A fringe of smaller scales is inserted along the marginal nervure. 
The “ pale-coloured down ” in the interior of the costal fold arises from 
the upper surface 1 (lit. “ wall ”), both of the marginal nervure and of the 
folded margin of the wing (Fig. 7). It is composed entirely of articulated 
hairs, with joints, which are mostly separated (Fig. 8), varying greatly in 
size, averaging 0*04-0*06 mm. long by 0*008-0*01 mm. broad : those which 
are united in greater or less numbers are usually very much narrower 
(Fig. 9). The joints are transparent, but with some dark dots. 
Telegonus mercatus , Fab. (PI. F, Figs. 10, 11).—The costal fold 
(Fig. 10 P) is smaller than in the two preceding species, only extending 
over about one-third of the anterior margin of the wing; its breadth is 
rather more or less than half that of cell 12 (adopting Herrich-Schaeffer’s 
term for the space between the costal nervure and the anterior [costal] 
margin of the wing). In the interior of the fold one finds a series of most 
curious scales (Fig. 11). Some, in the first place, represent the primitive 
form from which the others may be derived ; they are long, stout scales 
(Fig. 11 i ), about 0*3 mm. long, of which about one-sixth is taken up by 
the terminal triangular or oval lamina, the remainder by the stalk. Some 
are contracted below the terminal lamina, forming a sort of neck. In 
other similar but smaller scales (Fig. 11 g, h ), the neck is very much 
narrower, and the terminal lamina does not exceed, or even equal, the 
lower part of the stalk in breadth. The metamorphosis of the scales 
continues in the same direction (Fig. He,/) reaching at last a specialized 
form, in which the neck connecting the terminal lamina with the stalk, is 
reduced to a very fine thread (Fig. 11 c, d). Finally, there are scales, 
similar to the last-named, but ending in a fine, sometimes almost impercep¬ 
tible thread, without any terminal lamina (Fig. 11 5). 
It is certain that some of these scales were originally provided with a 
lamina, for I found loose several of these appendages, similar to the ones 
shown in Fig. 11 c, d. It seems to me, however, that some of the scales 
never possessed this structure, for the number of the separated laminae was 
not equal to that of the scales. 
Hesperia syrichthus , Fab. (PI. F, Fig. 12-18).—This species, which is 
not so prevalent in South America as in Central America and the southern 
parts of the United States, is very common in the province of Santa 
Catharina. 
The costal fold is somewhat large, and occupies the basal half of the 
costal margin of the wing, extending to the costal nervure (Fig. 12). 
1 The whole of the interior of the fold is of course the upper surface of the 
wing.—E.B.P, 
