NOTES ON A NEW LAND PLANARIAN. hy 
bordered by the glandular ridge of similar shape has nothing to do 
with the so-called ‘‘ Sinnesgriibchen,” but seems rather to be an 
artificial effect, due to the contraction of the radial parenchyme 
muscles, which are specially well developed in this region, and extend 
from the ventral side of the brain to the dermal layers forming the 
roof of the depression (see Plate IV., figs. 6 and 8). 
The structure of the single eye-like organ (see Plate IV., fig. 9, ao) 
at the head-tip presents some points of interest. Fig. 9 represents 
a median saggital section through a small portion of that region of 
the head which contains the organ. Here it is represented by a 
special clear part of the epithelium, which lies above a region of 
parenchyme, which is peculiar in having none of the fine pigment 
granules which are elsewhere present in great abundance. In this 
region the epidermis (ao) contains neither nucleated cells nor any 
sort of epidermal glands, but consists merely of a plasmic layer, 
which takes the stain faintly, and which contains minute vacuoles 
and irregular radial striations, as if to indicate cell boundaries. In 
the parenchyme underlying this part of the epidermis there are 
ordinary parenchyme-cells, together with a few muscle-fibres and 
numerous nerve-fibres (npl). There is also a thin cell-layer 
composed of slender nucleated cells, which lie vertically on the 
basement membrane and the dermal musculature. Owing to the 
inadequate fixation of the specimen, I have not been able to make 
out what relations exist between the outer non-nucleated plasmic 
layer and the inner nucleated layer. But from the close resemblance 
to the similar structures already described on the sensory margin, 
I am inclined to regard both layers as actually continuous with 
each other through the basement membrane. 
A striking feature of the present species is the presence of paired 
ciliated organs on the sole. Seen in sections the groove itself (Plate 
IV., figs. 7 and 10, co) is rather shallow, and is bordered on either 
side by a comparatively prominent ridge. The cilia which cover 
the surface of the organ as well as the sole (see Plate IV., fig. 10, s) 
are longest on the ridges, shortest on the sole, and of an intermediate 
length in the groove. The epithelium lining the groove and ridges 
is formed of nucleated cells, which stain fairly, and have a coarsely 
reticulated plasma. The nuclei are perceptibly smaller than those 
of the neighbouring epithelial cells. The ciliated epithelium which 
lines the groove and ridges does not contain any “ Stabchen” or 
epidermal glands, and is sharply separated from the overlying 
parenchyme by the distinct basement membrane and the two 
dermal layers (dm). The parenchyme in this region is rich in fine 
branches of the nerve fibres (see Plate IV., fig. 10, npl), which are 
probably connected with the ciliated organ. When I detected these 
curious organs, I supposed they might be something similar to the 
suckers of the Cotyloplanide. But this is merely superficial, since 
both organs are entirely different in their histological structure. 
