1886.] Grosse’s Classification and Structure of the Bird-lice. 347 
Malpighian vessels —These are four, not branched; have a 
lumen and ganglion-cells (not separated from the lumen by any 
membrane). 
Salivary glands—There are two pairs; and exceptionally the 
Philopteridas have one-celled glands as on the crop. Grosse 
found one of these cells undergoing division. The salivary or- 
' gans include salivary glands and salivary reservoirs. The glands 
usually adjoin the crop or stomach, and have a cell-layer with 
nuclei, covered externally and internally by a fine homogeneous 
epithelium. Before the entrance of thin ducts into the cesopha- 
gus, a gland and a salivary vessel unite into a common duct. 
Sexual organs.—The male sexual organs are of the usual type 
of insects, paired. testes, spermatic ducts, a seminal vesicle, ejac- 
ulatory duct and penis. Nerves supply the seminal vesicle and 
ejaculatory duct; and in Tetrophthalmus the terminal somite of 
the abdomen is withdrawn so as to be concealed, serving as a 
sheath for the penis. The female organs consist of paired ovaries 
(three pairs of ovarian tubes in Liotheide, five pairs in Philop- 
teridz), two oviducts uniting into one and a seminal receptacle. 
The egg-case has a lid which springs open at the exit a the 
young insect, 
Respiratory apparatus ——There are seven pairs of EE one 
in the prothorax and six abdominal. Each stigma has internally 
a crown of fine hairs to protect from impurities. A pair of strong 
longitudinal tracheæ send branches to the stigmata and are united 
to each other by a strong cross branch in the abdomen, and 
smaller ones in the he&d and thorax. 
Dorsal vessel—Grosse could not succeed in making a prepara- 
tion of this, but in the recently molted P animal it can be : 
seen pulsating through the back. _ oo 
Nervous system—This consists (in ae of two cephalic = 
ganglia and three thoracic ganglia. The precesophageal ganglion — 
is much larger than the subcesophageal, and they are united by 
strong commisures, The last thoracal ganglion is large, and a 
¿Sends back nerves to supply the abdomen. ~ 
Antenne.—In Liothèidæ these are four-segmented, club-shaped “oe 
or knobbed, the terminal segment spherical, lying in a hollow of — 
the Sub-terminal one (Fig. 1 af). In a cross-section of the ter- _ 
minal segment of Lzmobothrium are seen round nucleated oe oo 
apparently ganglionic enlargement of nerves. The Liot 
