384 WwW. A. HASWELL 
En arriere de cet ¢€paississement existe l’anneau chitineux 
auquel correspond une disposition particuliére des colonnes 
musculaires ; celles-ci, au lieu d’étre réguliérement radiaires, 
sont obliquement disposées, au moins dans le plan horizontal 
médian du proventricule, de fagon & agir dans deux sens per- 
pendiculaires. Cette disposition est destinée probablement a 
faire glisser et au besoin & comprimer fortement les aliments 
avalés par l’animal.’ 
A short distance behind the abrupt posterior edge of the 
thickened cuticle of the pharynx (fig. 5) is a deep transverse 
(circular) groove in the thick epithelium, and a little farther 
back a second similar groove, the two separated from one 
another by a prominent band of thickened epithelium. Just 
behind the posterior groove the cuticle is developed on either 
side into a dense chitimous plate. These plates are of no great 
length in the direction of the long axis of the body, but con- 
siderably elongated vertically, extending downwards so as 
to bound almost the whole of the slit-like lumen (Pl. 15, 
fig. 1). At the dorsal and ventral edges of each run grooves 
in the epithelium. Dorsally and ventrally these plates pass 
into the unmodified euticle which bounds the hunen of all the 
rest of the organ: anteriorly the same holds good, but pos- 
teriorly each plate projects a little beyond the general level 
of the surface, as the free edge of a finger-nail, elsewhere lying 
close on its bed, projects beyond the general surface of the 
digit. ‘The radial musele-columns of the wall of the proven- 
triculus in the belt through which these chitinous plates 
extend, depart from their arrangement in regular annular 
zones (fig. 5), and, as observed by Malaquin, run obliquely 
inwards and forwards or inwards and backwards. The object 
of this oblique direction would seem to be to enable the two 
plates to be tilted up so that their edges may be brought mto 
contact. 
VII. Tue Ventricuuus. 
The ventriculus is a small chamber, reduced or absent in 
some. It has fairly thick walls with a correspondingly reduced 
lumen. Numerous thin bundles of muscular fibres run radially 
