AS COMPARED WITH THOSE OF LIVING TYPES. 177 



the lower margin of the wing. In the under wing the variation is so great from this that 

 the main branch of the v. scapularis separates as a widely branching fork from the main 

 stem some little distance from the base, and continues straight on to the margin as the first 

 branch did in the upper wing, the main branch being then a fork from this straight one, and 

 branching as the main one did in the upper wing, except that it wants altogether the 

 second branch. 



Perldu. 



The v. mediastina runs parallel and pretty near to the v. marginalis until somewhat be- 

 yond the middle of the wing, when it turns suddenly at right angles and strikes the v. scap- 

 ularis, which has been running nearly parallel to it, though at a less distance from it, than 

 the v. marginalis. The v. scapularis continues on parallel to the v. marginalis, and runs into 

 it a little before it reaches the tip of the wing. The area marginalis is traversed by frequent 

 cross-veins ; the area scapularis has none. The v. scapularis gives off a branch generally half 

 way between the base and where the v. mediastina strikes it, which running sub-parallel to 

 the main stem terminates at about the tip of the wing, crossed at some point in its course 

 by another vein from the v. scapularis which generally (exc. Tceniopterix, etc.) continues on 

 and connects with the upper branch of the v. externo-media ; the branch of the v. scapularis 

 then divides into many branches, which are sometimes simple, sometimes again forked, and 

 sometimes have, in connection with the branches of the v. externo-media, recurrent forks. 1 

 The v. externo-media runs in very close proximity to the v. scapularis a little distance, and 

 then runs parallel to the branch, until it approaches the cross-vein from the v. scapularis, 

 when it forks, the forks sometimes again reforking. The v. inlcmo-media has a very indis- 

 tinct attachment at the base, being seen only from the under side, — is distant from the v. 

 externo-media, — has a considerable curve at its commencement, and very soon forks, the 

 upper fork running distant from, but nearly parallel to, the v. externo-media, gradually sep- 

 arating from it until near the forking of the latter, when it curves towards it and unites 

 to its lower branch ; it sends off rather distant cross-veins to its own lower branch, and 

 beyond emits many branches to the margin. The area interno-media is traversed sparingly 

 by cross-veins, sometimes in the fore wing only. The lower branch of the v. inter no-media is 

 simple, and diverges from the upper branch as that from the v. externo-media. The v. analis 

 is stout and forks at its origin ; the space between the forks enclosed near to the base by a 

 thick cross-vein which extends to the internal margin, and from mid-way between the 

 forks sends out a branch which runs between them, any or all of which branches and 

 forks may branch again, which they do to considerable extent in the hind wing, where also 

 there are more branches from the cross-veins. 



Ephemerina. 



Fore Wing. The v. mediastina runs near, and parallel to, the v. marginalis, extending to 

 the tip of the wing. The v. scapularis bears the same relation to the v. mediastina. The 

 v. externo-media runs parallel to the v. scapularis for a short distance, and is at the same dis- 

 tance from it as that is from the v. mediastina ; close to the base it sends out a branch, 

 which forks when it has reached two thirds of the distance to the margin, the lower branch 

 striking the outer margin at about the middle ; at less than one third the distance to the 

 tip of the wing the vein forks, the upper fork remaining parallel to the v. scapularis, while 



1 But in Capnia we have a very remarkable difference in that the main branch of the v. scapularis has its origin beyond 

 the cross-vein from the v. scapularis to the v. exler no-media. 



