L. Harrison 
123 
Taxonomic Value. 
The general constancy of the respiratory system in Mallophaga 
seems to me a good argument for allowing a fair amount of importance 
to such differences as occur. The points on which I lay stress are 
primarily the number of pairs of stigmata in the abdomen, together 
with their distribution on the abdominal segments; and, in the second 
place, the presence or absence of a posterior commissure. This com¬ 
missure when present is equal in calibre to the main trunks, and justifies 
the description of those forms which possess it as having a single 
continuous tracheal trunk, rather than two separate sub-parallel 
trunks. 
On the basis of the respiratory system, the Amblycera fall into 
seven groups: 
A. With five pairs of abdominal stig¬ 
mata (3-7) and a posterior com¬ 
missure ..... Trimenopon {Philandesia?) 
B. With six pairs of abdominal stigmata 
(2-7) and a posterior commissure . Fam. Boopidae 
C. With five pairs of abdonunal stigmata 
(3-7), no posterior commissure, and 
two head commissures . . . Gliricola 
D. With six pairs of abdominal stigmata 
(2-7), no posterior commissure, and 
two head commissures . . Fam. (3-yropidae (excl. 
Gliricola) 
E. With six pairs of abdominal stigmata 
(2-7) and only the usual four 
neural commissures . . . Fam. Ricinidae 
F. With six pairs of abdominal stigmata 
(3-8) and only the usual four neural 
commissures .... Fams. Menoponidae, Lae- 
mobothriidae, Ancistro- 
nidae 
Gr. With six pairs of abdominal stigmata 
(3-8), the usual four neural com¬ 
missures, and a transverse com¬ 
missure in the fourth segment . Tetrophtlialmua 
