154 WILLIAM BLAXLAND BENHAM. 
Fie. 4.—Surface of the region 4 of Fig. 1, viewed under a lens, showing 
the longitudinal striz. 
Fic. 5.—Enlarged view of the oral side of Ph. australis. Most of the 
tentacles of the outer series have been cut away, so as to expose the epistome 
(ep.), and to show the position of the mouth (m.). a. Theridge of the lopho- 
phore. 4. The basal region of the tentacular crown, in which the tentacles 
are united together. c. The free portions of the tentacles. 
Fic. 6.—Enlarged view of the anal side of Ph. australis. The tentacles 
are represented as being cut short. a. The lophophoral ridge. 0. United 
bases of the tentacles. c. Free portions of the tentacles. x. 7. Nephridial 
ridge. &. rv. Rectal ridge. 
Fic. 7.—The dorsal surface of Ph. australis. The drawing is to some 
extent diagrammatic, and greatly enlarged; the tentacles are cut away. The 
shape of the lophophore in this species is shown (cf. Fig. 12). a. Anus. D. 
Somewhat pit-like dorsal area. ¢. Epistome. g/. Glandular ridge, which 
follows the course of the lophophore along the dorsal surface of the inner 
series of tentacles. gi’. The glandular pit. 7. ¢. Inner series of tentacles. 
1. g. Lophophoral groove between the inner and outer series of tentacles, and 
continuous with m., mouth. z. 0. The right nephridiopore. 2. 7. Nephridial 
ridge. oo. ¢. Outer series of tentacles. &. r. Rectal ridge. sp. The 
ascending spirally-wound lophophore. «. Break in the inner series of 
tentacles. 
Fic. 8.—Transverse section through the glandular pit (g/., Fig. 7). ep. 
Epidermis, covering the bases of the tentacles. Outer wall of the pit com- 
posed of several layers of cells, the inner epithelium being ciliated. gd. 
Glandular cells, forming the inner wall of the pit and continued round the 
lophophore as the glandular ridge. yp. The cavity of the glandular pit. 7. ¢. 
Tentacular cavities. ¢. Trabecule. 
Fic. 9.—A portion of a transverse section of the body wall. 4. ¢. Basement 
tissue, showing one of the cells (¢.) which are scattered in it. cz. Circular 
muscles. ep. Hpidermis. g. Goblet-cells. /g. Longitudinal muscles. p. Pig- 
ment granules. 
Fic. 10.—A portion of a longitudinal section through the body wall in the 
bulbous region, marked 4 in Fig. 1, in order to show the inversion of’ the 
muscular layers. The arrow indicates the direction in which the tentacular 
crown lies. 4. ¢. Basement tissue. cw. Cuticle. ep. Epidermis (here con- 
siderably thicker than over the general surface). cz. Circular muscles, in the 
usual position. cz’. The circular muscles which become placed internally. 
lg. The longitudinal muscles. /y’. The internally placed longitudinal muscles. 
ce. Colomic epithelium. 
Fic. 11.—A portion of a transverse section of the epistome. «ad, Anal or 
dorsal surface. ov. Oral surface, covered by ciliated epithelium. c. Ccelom. 
nm. Nerve. sk. Skeleton, continuous with the basement tissue. 
