224 
typical number in butterflies*), and that of these, two (2c and 2d) are 
united into a fork near the tip of the wing, the base of which fork 
extends backward to the upper exterior angle of the discoidal cell, 
from which also a simple vein (2e) extends to below the extremity of 
the wing ; below these is another simple branch (x) emitted from the 
middle of the extremity of the discoidal cell, then two others (y and 
3,,) united into a fork with two simple branches beneath (3,, and 3,,). 
These letters indicate the analogies which I consider these various 
branches to possess with those of the butterflies, and adopting the 
nomenclature of Mr. Edward Doubleday, the fork (2¢ and 2d) must 
represent the third and fourth branches and 2e the extremity of the 
subcostal vein, x the upper discoidal, y the lower discoidal, and 
3,, 3,, 33, the three branches of the median vein. Here however, 
as in so many places elsewhere, we are met by the difficulty pre- 
sented by the two discoidals; y in the species before us, forming 
unquestionably (so far as function is concerned) a portion of the 
system of the median vein. The more I investigate this subject, 
the less do I feel convinced of the propriety of regarding these 
two discoidals as having a distinct system of their own, feeling on 
the other hand that the upper discoidal, x, belongs to that of the 
subcostal, and the lower discoidal, y, as here, to that of the me- 
dian vein. In this point of view, the figure which Zeller has just 
published of the veins of the wings of Auxocrossa Hopfferi, from 
Para (Linn. Entomol. ix. tab. 3. fig. 25), is a perfect type of the 
system of the veins of the wings of Lepidopterous insects. Here 
are, as usual, twelve terminal branches, the costal and submedian 
simple, the postcostal with five simple branches and its own terminal 
portion, and the median with four simple branches, the two composite 
systems being quite separate from each other, there being no trans- 
verse veinlet to close the discoidal cell, which is consequently open 
as in many butterfliest; but in these latter we are met by the diffi- 
culty that the fourth or anterior branch of the median (or the lower 
discoidal of E. Doubleday, y) is pushed forward and becomes, toge- 
ther with the upper discoidal, v, portion of the system of the sub- 
costal vein. We may cut this knot either by supposing that these 
two contiguous branches belong to either one or other system (which 
accords with the views of Lefebvre), or by considering that sometimes 
one or other of these systems occasionally throws out another branch, 
the other system in such case being deficient in a branch, which is 
scarcely maintainable, seeing that out of the hundreds of Lepi- 
* It is astonishing, with so many examples before him in which this typical 
number is reproduced, that M. Alex. Lefebvre, in his imaginary type of a Lepidop- 
terous fore wing (Ann. Soc. Ent. Fr. xi. pl. i.), should have given only eleven as 
the typical number. 
+ Parasia Carlinella (Stainton, Ins. Brit. Lep. pl. 4. fig. 6a) is another instance 
of the separation of the two systems of veins: the subcostal, consisting of five 
branches and a terminal portion; and the median of four branches, without any 
discoidal veinlet, but the cell is imperfectly closed. Asychnia modestella (ibid. 
pl. 8. fig. 1a) is another example of the separation of the two systems without 
any discoidal veinlet, but here the median has only two and the subcostal only 
four branches and a terminal portion. 
