PLANARIANS FROM MAURITIUS AND RODRIGUES 139 
short, columnar cells, each bearing a large number of short cilia 
onits outer surface. Inno cases have I been able to demonstrate 
rod-like bodies, wedged in between the cells. Deeply situated 
in the parenchyma there are enormous quantities of slime glands, 
which open to the exterior all over the surface of the sole. 
Basement Membrane.—The basement membrane, 
which is in connexion with the epidermis, is distinctly visible as 
a very thin, structureless, homogeneous layer. It is perforated 
at various points by the passages of the rhabdite-forming cells 
and the glands which lie deep down in the parenchyma. 
Muscular System.—tThe musculature of the body, as is 
well known, is differentiated into two systems, superficial and 
deep. 
The superficial muscular system consists, as usual, of circular, 
transverse, and longitudinal fibres. Immediately beneath the 
basement membrane is a thin muscular layer made up of closely 
apposed circular fibres. The transverse fibres, crossing those 
of the other set obliquely, are just inside the circular layer. The 
longitudinal fibres form a thick layer, the external longitudinal 
layer, which is more strongly developed on the ventral surface 
than on the dorsal. The muscles appear separated into a series 
of bands, each made up of a few fibres. Through the intervals 
between the bands the rhabdites and the glands make their way 
to the surface. 
The deep muscular system, separated from the superficial by 
a zone of tissue, forms a layer thicker than the latter, and 
consists principally of two distinct sets of fibres, longitudinal 
and circular, which occur intermingled in the same mass, 
without being arranged in definite layers. The longitudinal 
fibres are more strongly developed than the circular. In addition 
to these dorso-ventral muscles are found, which run between 
the branches of the imtestine. 
Parenchy ma.—the tissue filling all the interspaces be- 
tween the various organs and structures assumes, as usual, the 
appearance of an irregular network, in the ground substance of 
which is found a number of nucleated cells of a more or less stel- 
late shape. Embedded in the superficial parts of the dorsal 
