150 
MR. H. N. MOSELEY ON THE ANATOMY AND 
Description op the Plates. 
PLATE X, 
Fig. 1. Bipalium Ceres , sp. nov., of the natural size, from specimens preserved in abso- 
lute alcohol. 
Fig. 2. Young of the same, from the same source. 
Fig. 3. Young of Bipalium Diana , from specimens preserved in absolute alcohol, and 
of the natural size. 
Fig. 4. Rhyncliodemus Thwaitesii , sp. nov. 
All four specimens from the Royal Botanic Gardens, Peradeniya, Ceylon ; drawn of the 
exact dimensions. 
Fig. 5. Vertical section of Bipalium Diana , taken in a direction transverse to the long 
axis of the body, at a spot about half an inch distant from the anterior margin 
of the animal’s head. Drawn with a camera lucida. 
* The letter D, seen a little above the middle of the figure, is placed in the 
central digestive cavity, which in that portion of the body which is anterior to 
the entrance of the pharynx is single, as is ordinarily the case in Dendroccelous 
Turbellaria. The cavities lettered D' on either side of it represent the 
lateral diverticula which it gives off : as they are not given off quite at right 
angles to the central stem, they are not exposed in their entire length in a 
transverse section such as this. Between the letters D and D' are seen portions 
of the septa which separate the successive diverticula and their branches from 
each other, and show decussating muscular fibres very plainly. The clear 
spaces (W) on either side the middle line, inferiorly to the origins of the lateral 
diverticula, are the two chief trunks of the water-vascular system, running 
antero-posteriorly, and are less stained with carmine than the rest of the 
section. The glandular masses (T) lying immediately exteriorly to them are 
the testes ; in the interval between each testis and the water- vascular trunk 
is seen the vas deferens (V.D.) in section, and in the upper and outer angle 
of the water-vascular trunk is seen the oviduct (OD). The inferior surface of 
the body is flatter than the superior; but a considerable projection is formed 
along the middle line of the surface by an “ambulacral line” or “sole,” whence 
these Turbellaria are sometimes termed “ gasteropodous ” (Diesing, loc. cit. 
p. 509). Where the ambulacral line rises above the level of the rest of the 
inferior surface of the body, cilia of large size are seen to clothe it. A zone 
of tissue, contrasting by its greater clearness with the cuticle and its basement 
membranes and muscles, runs round the whole body of the animal immediately 
internally to those structures. This greater clearness is due to the absence 
in this zone of the longitudinal layer of muscular fibres, which is largely deve- 
loped both internally and externally to it. The area of the zone itself is 
