NEW RHABDOCCELE COMMENSAL WITH MODIOLUS 373 
at eyes 0.28; distance between eyes 0.10; distance of eyes from 
anterior end variable, but most of the time about 0.14; pharynx 
nearly circular in outline and about 0.09 in diameter; ciliated 
young very variable in life, on account of contraction changes; 
but usually 0.12 to 0.14 in length; diameter of a capsule containing 
a pair of young 0.11. A small specimen without young, slightly 
compressed, measured 0.56 in length and 0.32 in breadth, and the 
diameter of the pharynx was 0.04. A large specimen, which was 
in a moribund condition, semi-transparent, turgid and devoid 
of cilia, measured 1.75 in length, 0.37 in breadth at the eyes, 
0.63 at the middle, and 0.28 near the posterior end. 
NOTES ON THE ANATOMY OF THE SPECIES 
It is not my purpose to give histological details; indeed, my 
material, although consisting of numerous whole mounts and a 
number of series of sections, while enabling me to understand much 
of the anatomy, still leaves much unexplained. 
Epidermis, etc. 
The epidermis is ciliated, the cilia appearing in the embryos 
before the pigmented eye-spots are seen. The cells are irregu- 
larly cubical with large nuclei. In cases where the epidermis 
was seen in living specimens crushed under the cover-glass the 
outlines of the cells were very irregular. Four sets of muscle 
fibers can be distinguished in sections from material which was 
fixed in Flemming's chrome-osmo-acetic fluid and stained in iron 
haematoxylin. These are longitudinal, transverse, and two sets 
of diagonal fibers (fig. 15). There are no rhabdites, and I fail 
to recognize the subhypodermal glands which are said to be 
present in the parasitic turbellarians. 
In the living worm, under favorable conditions, there may be 
seen a reticulum of slender strands uniting here and there into 
masses of similar substance, the whole resembling a plexus of 
fine nerve-fibers with interspersed ganglia (figs. 13, 14). No 
nuclei were observed in these masses. The strands are solid, and 
