STRUCTURE OF THE MALLOPHAGA. 165 



ventral (Fig. 2, ds.^ vs.). The ventral piece has posterior processes 

 joined by muscles with the occipital border. The dorsal piece 

 sends forward a muscular bundle, which bifurcates, and its divi 

 sions are inserted on the anterior cranial border. Two ducts 

 (probably salivary) run forwards through these scale-like pieces, 

 uniting into one. The chylus-stomach is cordate at its beginning, 

 and has no chitinous intima. The hind intestine has six longitu- 

 dinal grooves and rectal glands, with richly branching tracheae and 

 a chitinous intima. 



The mode of nutrition of Mallophaga is not fully ascertained. 

 Nitsch stated that they eat the epidermal products of birds and 

 mammals, and sometimes blood. Grosse finds that blood is 

 rarely taken, and only in cases where the bearers (birds) are so 

 injured or diseased as to have blood among their plumage ; and 

 Leuckart gives the same result as to Trichodedes canis of the dog. 

 In Lcemobothrium., Grosse found the intestine filled with the limbs 

 of its own kind, as if it ate the product of its own moulting. 



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 

 Philopterid^ have one-celled glands as on the crop. Grosse 

 found one of these cells undergoing division. The salivary organs 

 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 epithe- 

 lium. Before the entrance of thin ducts into the oesophagus, 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, ejacu- 

 latory 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 the abdomen is withdrawn so as to be concealed, serving as a 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 Liotheid^, five pairs in Philop- 

 terid/e), two oviducts uniting into one and a seminal receptacle. 

 The egg-case has a lid which springs open at the exit of the young 

 insect. 



VOL. V. N 



