no 
The Respiratory System of Mallophaya 
larger vestibule which in turn opens into a second chamber, or bulla, 
the latter receiving the narrow end of the stigmatic trachea. 
The external aperture is usually circular, sometimes ellipsoid, in 
which case the long axis is usually transverse, or slightly oblique. Its 
size varies considerably, as the following table of measurements shows. 
Where the aperture is not circular, the longer axis has been measured. 
Diameter oe Abdominal Spiracles in Millimetres. 
Lipeurus circumfasciatus 
0-006 
Oxylipeurus sinuatus 
0-014 
Giebelia hexakon 
0-008 
Trabeculus heteracanthus 
0-014 
Tridiodectes appendiculatus 
0-011 
Gyropus ovalis 
0-015 
Goniodes curvicornis 
0-011 
Lipeurus crassus 
0-015 
Lipeurus mutahilis 
0-011 
Orn.ithobius fuscus 
0-017 
Lipeurus diversus 
0-011 
Heteroproctus hilli 
0-017 
Degeeriella cingulata 
0-011 
Docophoroides brevis 
0-017 
Rallicola bisetosa 
0-011 
Pseudomenopon tridens 
0-017 
Aptericola gadowi 
0-012 
Tridiodectes setosus 
0-028 
Goniocotes fissux 
0-012 
Lipeurus ferox 
0-033 
Pliilopterus occidentalis 
0-012 
Heterodoxus longitarsus 
0-039 
Glirieola gracilis 
0-013 
Philopterus brevicollis 
0-039 
Latumcephalum macropus 
0-014 
Tetrophthalmus titan 
0-047 
Lipeurus asymmetricus 
0-014 
Laemobothrium circi 
0-055 
A study of this table shows that, in general, the stigmatic apertures 
of the IscHNOCERA are considerably smaller than those of the Ambly- 
CERA. The exceptions which stand out prominently are Tridiodectes 
setosus, which, in common with most species of the genus, possesses 
large stigmata; and Pliilopterus brevicollis, which belongs to a small 
group characterised, amongst other things, by the size of the stigmata. 
But it is not until after eight Ischnoceran genera are listed that the 
first Amblycera appear, and these are Latumcephalum and Glirieola, 
both very small forms. Laemohothrium caps the list, but in proportion 
to its size has small stigmata. The same may be said of Ricinus. 
Forms found upon mammals have, in both sub-orders, larger stigmata 
than those found upon birds. Seen in profile (Fig. 9, B) the stigma 
exhibits a rigid rim standing up from the general surface. The external 
opening is never protected by hairs, though in Tetrophthalmus (Fig. 10) 
certain bristles occur in close proximity. 
The prothoracic stigmata differ, as a rule, in their larger size, and 
in having the actual external aperture slit-like rather than circular or 
ellipsoid. Several forms are shown in Figs. 11, 12, 13, 14. They are 
situated ventrally upon the prothorax, close to the postero-lateral 
