XEROPHILA VIRGATA. 147 
edges converge rapidly to the point. Below the angulation they gradually diminish 
and blend with the stem of the dart, about half-way down the weapon. In imma- 
ture darts the blades only extend one-third or one-fourth the length of the dart, 
and at a still earlier stage no blades are visible. The shaft is usually marked 
transversely with coarse irregular bands or ridges, resembling lines of growth 
placed at irregular distances from each other, and varying in depth of whiteness. 
The base is the widest part of the shaft, but there is no abrupt expansion. 
The figure from Schuberth of the gypsobelum of Xerophila variabilis shows a 
very different weapon, whose aceuracy should be confirmed. 
The SPERMATOPHORE resembles a spirally twisted filament of sill; it is about 
18 mill. in length, and forms about two whorls with a row of upwardly directed 
marginal denticles on the anterior half, and is evidently moulded in the twisted 
epiphallus, the flagellum being too short to account for more than 2 or 3 mills. of 
Fic. 232. Fic. 233. 
Fic. 232.—Spermatophore of X. virgata, showing its spirally twisted form, x 4. 
Fic. 233.—Spermatheca of XY. virgata, after conjugation, showing the distortion of the vesicle 
and its duct by the contained and rigidly spiral spermatophore, x 3. 
its length. In drying the spiral part quickly hardens and distorts the spermatheca, 
and sometimes the duct or stem is also contorted by the slender, thread-like, coiled 
posterior end which hardens immediately when exposed to the air. 
The ALIMENTARY SYSTEM is of the triodromous type, the GSOPHAGUS is long 
and encircled about midway of its length by the SALIVARY GLANDS, whose ducts 
are long, slender, and white; the Crop is elongate, usually brown in colour, and 
Fic. 251: 
Fic. 234.—Alimentary system of . wixgata Da Costa, showing the buccal bulb, salivary glands, 
salivary ducts. the triodromous type of gut, etc., x 3. 5 
blends with the STOMACH. which terminates the cesophageal tract; the GUT forms 
the usual reversed S-like coil before entering the straight rectal tract. 
The MANDIBLE or jaw is of a more or less ecrescentic shape, and of a fawn 
colour, the ends are rounded and thinner than the medial portion. It is about 
14-2 mill. wide, with 5 to 10 prominent transverse ribs, which are usually confined 
to the medial portion, the ends being generally smooth and free from ribbing, which 
Fic. 235. Fic. 236. 
Fic. 235.— Mandible of X. virgata, from Chipstead, Surrey, prepared by Dr. E. W. Bowell, x 20. 
Fic. 236.—Mandible or jaw of \. vixgata, from Beverley, Yorkshire, prepared by Mr. J. Darker 
Me 
Butterell, showing narrower and more numerous transverse ribbings, x 18 
usually denticulate the upper and lower margins. Intermediate and _ slightly 
developed ribs are sometimes present on the jaws of the older animals, and in some 
the ribs only crenulate the lower or cutting margin. _Moquin-Tandon describes the 
jaw of H. variabilis as bearing from 15-20 ribs, and that of H. lineata as having 
7 to 9 only. 
