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hole (b) and is radiately striped from this hole; the 
immediate surrounding of the hole is very light, suc- 
ceeded by a darker, not distinctly limited ring. The 
hole is leading into a respiratory cave (fig. 3, d), 
the interior wall of which consists of an integument, 
fastening itself round along the edge of the elevated 
portion of the integument of the leg; the exterior wall 
being thus convex and the interior one concave into 
the leg, a real cave has arisen. A tracheal trunk is 
opening itself through the interior wall, the aperture 
(fig. 4, e) is a little larger than the aperture of the 
spiracle itself and situated closer up to patella. The 
distal spiracle is constructed quite in the same way 
(fig. 6), the outlet of the tracheal trunk (e) is, however, 
nearer to metatarsus than the aperture of the spiracle. 
On both spiracles the interior wall of the respiratory 
eave (fig. 5) is studded with numerous larger and number- 
less very small spines, all radiating towards the outlet 
of the tracheal trunk. 
I had for some time examined Phal. cornutum L., 
but did not succeed to make out this structure, before | 
had taken to the study of the spiracles in the large 
females of Phal. propinquum Luc. which I recommend 
as an excellent object for this examination. 
Next arises the question as to the relation of these 
spiracles to the tracheal system of the animal. In the 
literature it is stated that Phalangtoide have but one 
single pair of spiracles, lodged almost behind the middle 
of the coxæ of the hindmost pair of legs, and from each 
spiracle a very wide tracheal trunk issues forward in 
the body, dividing itself into several thick branches. 9 
tracheal trunks go into each leg and are easily seen 
especially inside the femur, the one is a little wider 
than the other; they do not unite towards the basis, 
but issue each from its own branch of the main trunk 
