1903.] ANATOMY OF A NEW GEPHYREAN WORM. 33 
series of papillee whose epithelial covering is apparently devoid of 
cilia. 
For the reason mentioned at the beginning of this paper, it was 
no easy matter to gain a certain knowledge of the histology of the 
alimentary tract. Figure 9 A (Plate VII. ) shows the character of 
the epithelium of the mid- -gut generally : lying upon the thin mus- 
cular wall are narrow cells of varying length, with a basal nucleus 
and granular cytoplasm; the outlines between the several cells 
were in many places most indistinct. The epithelium of the rectum 
(fig. 9 B) is composed of cubical cells, with a distinct margin on 
the surface next the lumen of the gut. They possess cilia, and 
were the only cells in the alimentary tract in which the presence 
of a ciliated border could with certainty be determined, 
Circulatory System. 
This consists of a dorsal vessel, a sinus surrounding the base of 
the tentacles, and tentacular vessels. 
The dorsal vessel is single, and though convoluted it is devoid 
of diverticula: coursing along the dor Aol wall of the fore gut, it 
surrounds the base of the fentacles with a cireular sinus into 
which the brain dips (Plate VIII. figs. 11, 15, 16); from this 
circular vessel tentacular sinuses arise, they form noticeable 
objects in sections of the tentacles (Plate VII. fig. 8, B.8.). 
Nervous System. 
This is of the usual type, and consists of a brain, a ventral 
nerve-chain, and a couple of sense-organs. 
The brain is a small, somewhat cordiform body, measuring in its 
long axis, which corresponds with that of the animal, three-tenths 
of a millimetre; it les on the dorsal wall of the pharynx at the 
base of the tentacles; it is surrounded by a fine capsule of con- 
nective-tissue, and the anterior surface in addition is covered by 
an epithelium (Plate VIII. fig. 13, E.), which is continuous with 
that of the outer non-ciliated aspect of the tentacles; laterally, the 
muscular tube formed by the union of the retractors abuts upon it 
(fig. 15, R.M.); below the brain is the blood-sinus (B.S., figs. 11, 
13, 15) from which the tentacular vessels arise. 
The majority of the cerebral cells are small, with a clear cyto- 
plasm and relatively large nuclei; they are massed anteriorly, 
dorsally, and posteriorly: the central and greater part of the 
ventral aspect of the brain are composed of fibres, but behind 
the point of origin of the circumcesophageal commissures there 
are to be seen in the lower cortical part several very large 
ganglion-cells (G.C., fig. 11): these giant cells measure ‘03 mm. 
in diameter; some are pyriform, others irregular in shape, and 
these appear to be multipolar, unlike those of Phymosoma 
(Shipley, No. 7%"), but on this point I cannot be absolutely 
definite. 
? This number has reference to the list of authors quoted on p. 40. 
Proc. Zoou. Soc.—1903, Vou. I. No. III. 3 
