32 
rent aspect. Instead of a thin continuous chitine layer with the 
spiral ribs (tænidia) presenting themselves in cross section as square 
or semicircular outgrowths from it we find here the chitine wall 
with unbroken parallel sides, the section of the wall itself presen- 
ting a transversal striping. Stained 
with hematoxyline and eosine some 
of the stripes appear with a deep 
purple tint, absorbing both colouring 
matters equally well, the remaining 
stripes show only a very faint pink 
tinge from the eosine. By exami- 
nation with high power we find this 
pink part forming not only rather 
narrow stripes alternating with the 
broader purple ones, but also an 
apparently continuous outer (distal) 
layer of the whole air-bladder. But 
in reality this layer is not quite 
continuous, it is formed by the wide- 
ning of each of the narrow stripes 
Fig. 4 arr omen sections ofthe walls beyond the distal end of the purple 
dt => NERE So wall; mmgn ok LG Stripes so as to form a mare gf 
thickness 38,0 ,;, chitine 21,1 ,/4, outer dark less rounded head which generally 
ne SS Se. Sek el RE abuts against the two neighbouring 
2,1 u, grey stripes 0.7 4. B: section of the heads; the limit between them is 
male be sene ran bb: SE W always seen as a faint dark line, 
dark line 0,3 4, «heads> 1,8 1, dark stri- and not unfrequently they are sepa- 
SAR sl us ig nei ve inleege ig rated from each other by a narron 
narrowing and the «heads» diminishing interspace; but perhaps this is only 
und Br ere ig Cam. luc. an artificial product due to a shri- 
velling of the tissues in alcohol. The 
distal ends of these heads together form an undulating line bor- 
dering on the epithelial sac. — The purple stripes are 17/2——3 times 
as broad as the pink ones, their distal end is convex, the proximal 
end slightly convex or straight, forming together with the proximal 
end of the pink stripes a slightly undulating or straight line. 
These stripes are broadest and most distinct in the ventral wall 
of the air-bladder, somewhat narrower, but still very distinct in the 
