PROBOSCIS OF SYLLIDEA San 
EXPLANATION OF PLATE 15. 
Letlering common to all Figures. 
an., annular bands of non-striated muscle ; a.pr.g., anterior proventri- 
cular glands; a.r., accessory radial fibres ; ¢.p., chitinous plates of pro- 
ventriculus ; cw., cuticle; e.m., external membrane; ep., epithelium ; 
i., intestine ; i.m., internal membrane; p., pharynx; pa., pharyngeal 
papillae; p.g., pharyngeal gland; pr.v., proventriculus;  pt., post- 
ventriculus ; 7., radial muscle-columns. 
Fig. 1.—Diagram of a transverse section of the proventriculus of Syllis : 
about one quadrant shown. The section is represented as passing through 
the chitinous plates; but the typical arrangement of the muscles is 
illustrated—not the modified arrangement in the chitinous plate region 
(see fig. 5). The coelomic epithelial layer is not represented in this or the 
other figures. 
Fig. 2.—Part of a transverse section of the proventriculus of Syllis 
variegata (Grube). x330. The dark transverse lines passing across 
the radial muscle-columns indicate the telophragms. The accessory 
radial (a.r.) fibres are drawn in black, as in the other figures, for the sake 
of contrast. 
Fig. 3.—Portion of a tangential section of the proventriculus of 
S. variegata internal to the annular bands. x 330. The pattern of 
the transverse sections of the cortex (‘Cohnheim’s areas’) is not repre- 
sented in this or in the following figure. 
Fig. 4.—Portion of a tangential section of the proventriculus of 
S. coruscans (Haswell), internal to the annular bands. x 330. 
Fig. 5.—Part of a horizontal section of the proventriculus of Syllis 
closterobranchia (Schmarda), passing through the chitinous plates. 
x 330. 
Fig. 6.—Diagrammatic general view of the proboscis of a Syllis 
_ from above: part of the dorsal wall of the pharynx and proventriculus 
removed to show the region of the anterior proventricular glands and the 
chitinous plates. Only one of the pharyngeal glands is represented. 
a.pr.g., anterior proventricular glands ; ¢., caeca; ¢.p., chitinous plates ; 
cu., thickened cuticle of the pharynx; 7., intestine; p., pharynx ; 
pa., pharyngeal papillae ; p.g., pharyngeal gland ; pr.v., proventriculus ; 
pt., post-ventriculus. 
Vig. 7.—Semi-diagrammatic view of a horizontal section through the 
junction of the pharynx and proventriculus of Grubea to show the 
position and relations of the anterior proventricular glands, x 780. 
