118 Psyche [December 



transverse rows of backward-directed bristles (PI. 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 (PI. 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 (PI. 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 (PI. V, m. d.) and at each of its basal angles a 

 single sharp lateral denticle (1. d.). Immediately in front of the 

 median tooth is a pair of lateral teeth (1. t.) ; viewed from the inner 

 side ( i. 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 stiff er hairs. Next the chitinous partition on 

 each side is another brush-like process (o. b. 1.) bearing a very 

 sharp backward curving tooth. The two last described processes 

 are termed by Berlese / lohi 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. 



