118 Psyche [December 
transverse rows of backward-directed bristles (Pl. V, br.), a few of 
these bristles, especially in the posterior rows, occasionally develop 
into small chitinous teeth. The tunic of circular muscles (c. m.) is 
only two or three layers thick and in each fold there is a band of 
longitudinal muscles (Pl. V, Fig. 2. r. m.). 
The posterior division of the proventriculus is broadly oval and 
contains a complicated system of strongly chitinized teeth. The 
tunic of circular muscles is well developed, consisting in some 
places of ten or twelve layers. Within are six dental folds 
continuous with the folds in the anterior portion. These folds 
are separated by means of chitinous partitions (Pl. V, ch. p.). 
In each dental fold there are normally ten transverse rows. 
of teeth, each row consisting of seven distinct teeth all directed 
backward towards the mesenteron. In the middle of the fold 
is the median tooth (m. t.), the only unpaired tooth in the row 
and the one which projects farthest into the lumen. At its. 
apex it bears four to six sharply pointed, strongly chitinized 
median denticles (Pl. V,m.d.) and at each of its basal angles a 
single sharp lateral denticle (I. d.).. Immediately in front of the 
median tooth is a pair of lateral teeth (1. t.); viewed from the inner 
side ( 7. e., from the direction of the median tooth) these teeth are 
narrowly wedge-shaped; from the outer side they present a narrow 
curved surface around the edge of which are arranged eight small 
chitinous processes which convert this tooth into a grinder com- 
parable to a molar. Behind the median tooth is a pair of large 
blunt pad-like processes (i. b. 1.) not very highly chitinized as com- 
pared with the median and lateral teeth, and covered for the most 
part with a short yellow pubescence but on the anterior side with 
rather longer and stiffer hairs. Next the chitinous partition on 
each side is another brush-like process (0. b. 1.) bearing a very 
sharp backward curving tooth. The two last described processes 
are termed by Berlese i lobi a spazzola so the writer has called them 
respectively the inner and outer barbated lobes. 
The cells of the single epithelial layer of the chitinous partitions 
are clearly marked off. The epithelial cells of the various processes 
are not so distinctly marked, the numerous nuclei of the epithelium 
being very closely packed. Within each row of teeth there is a 
muscular band (PI. V, Figs. 4 and 5 r. m.) which pulls the teeth 
outwards, enlarging the lumen and opposing the action of the 
circular band. 
