L. Harrison 
107 
Museum. Living material has, however, not been available in the 
majority of cases, but the forms which have been examined in detail 
show such a remarkable constancy in their tracheal arrangement that 
nothing of any great interest and importance is likely to result from 
further detailed comparisons. These forms include species of Gliricola, 
Gyropiis, Heterodoxus, Menopon, Menncanthvs, Myrsidea, Ricinus, 
Degeeriella, Goniodes, Goniocotes, Lijienru.s, and PMloptervs. The 
genera which I have not been able to examine are Damalinia, Eutricho- 
philus, Trichophilopferiis, Eiirytrichodectes, Philoceanvs, Kelloggia, Or- 
nicholax, Bothrioynetopns, Trochiloecetes and PJiilandesia. Of these 
the first four will certainly not differ very much from Trichodectes; 
the fifth, sixth and seventh, and eighth from other Giebeliidae, Gonio- 
didae and Akidoproctidae respectively; and the ninth from Rieinvs. 
Philandesia may prove on examination to present some features of 
interest, but it is the only distinctive genus excluded from my examina¬ 
tion. 
The generalisations which I shall proceed to make as to the number 
and disposition of the stigmata and main tracheal vessels are based, 
then, on observations of species belonging to forty-one genera in a total 
of fifty-one. The ten not examined are in the majority of cases mono- 
typic; in seven cases only recent cleavages from larger genera with 
which they show a very close agreement; and number less than twenty 
species in a total of close upon two thousand. 
The Stigmata. 
In all Mallophaga except Gliricola and possibly Trimenopon there are 
seven pairs of stigmata, one prothoracic and six abdominal. Gliricola 
has but five pairs of abdominal stigmata. I have been able to examine 
only mounted specimens of Trimenopon, and in these I have not suc¬ 
ceeded in demonstrating the existence of a sixth abdominal pair. 
I also find one species of Trichodectes, T. divarieatus, Neumann, vfith 
only five pairs of stigmata apparently present. I do not know of any 
other exception to this general statement, which, although several 
morphological accounts of the Mallophaga have been published, has 
not been made before. All that Snodgrass (1899, p. 170) says about 
the stigmata is: “ Spiracles are situated laterally on the dorsal side 
of the abdominal segments, and in some species, as Menopon titan, 
there is a spiracle on each side of the prothorax.” The italics are mine. 
Mjoberg (1910), as already stated, only demonstrated prothoracic 
