INNERVATION OF INTEGUMENT OF CHIROPTERA 311 



The main blood vessels, accompanied by the chief nerve 

 trunks, pass out from the body through the flying and inter- 

 femoral membranes in the stratum reticulare, giving off, here and 

 there, important branches, which, as stated, are frequently 

 found with the muscle bundles. These blood vessels, partly 

 because of their own size, and partly on account of the increased 

 amount of connective tissue around them, cause the elongated 

 thickenings or ridges already referred to in these membranes. 

 The meduUated nerve trunks and their chief branches, both 

 found in the innermost stratum (reticulare) and existing only 

 in the aforesaid ridges, constitute the first nerve layer". The 

 second, a double layer of nerves, arises from the first by repeated 

 dichotomous branching, traverses the deeper part of the corium, 

 and spreads throughout the entire area of the flying and inter- 

 femoral membranes. In methylene blue preparations this layer 

 is seen to consist of a loose network of medullated nerve fibers, 

 many of which contain comparatively large varicosities (fig. 13, va) . 

 The third and last nerve layer is likewise double. Numerous 

 medullated fibers arising from the second nerve layer pass toward 

 the two external (dorsal and ventral) surfaces of the membranes. 

 Many of these fibers, on approaching the Malpighian stratum, 

 divide dichotomously ; others do so at the surface of the corium. 

 Both lose their medullation. The forked branching continues 

 to some extent in the Malpighian stratum, the larger fibrils giv- 

 ing off smaller ones, until finally delicate nerve threads end in 

 minute enlargements, which will be described in detail later. 

 These branchings of non-medullated nerve fibrils at the surface 

 of the corium and in the stratum Malpighii constitute the third 

 nerve layer. While varicosities of different sizes (figs. 13, 14, 15) 

 appear in the nerve fibers leading up to this layer, the writer has 

 not observed them in the latter. 



According to the present observations, then, certain regions 

 of the flying and interfemoral membranes are supplied with three 

 layers of nerves, others with but two. Briefly stated their 

 number and distributiofi are as follows: 



1. A layer of medullated nerve trunks and numerous medul- 

 lated branches, occurring in the stratum reticulare, but only in 



