HISTOLOGY OF THE LAND-PLANARIANS OF CEYLON. 
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glandular masses are well developed all over the body, except on the ambulacral line: 
at the sides of this organ, where the long cilia are, they are quite absent, but a very 
few are occasionally to be seen along its median line. In the head of Bipalium there 
is an unusual development of the internal glandular system, as will be seen by reference 
to Plate XIV. fig. 3. In longitudinal sections of the body taken in a direction parallel 
to its ambulacral surface, there may be observed in the region of the mouth an irregular 
tree-like arrangement of the internal glandular masses, but no definite duct or termina- 
tion of this glandular tree was to be discovered. 
Remarkable Glandular Masses in Bipalium Ceres. — In Bipalium Ceres a remarkable 
structure was met with which could not be found in either of the other species of 
Bipalium examined. 
In this species, on the ventral surface, is a pair of peculiar ridges which run longi- 
tudinally along the entire length of the body. The ridges are situate at the line of 
junction of the convex superior surface of the animal’s body with its flatter ventral 
surface. When viewed with a lens, these ridges merely appear as elevations or 
pinchings up of the integument. They were present in all specimens of Bipalium 
Ceres examined. In vertical sections of the body of this species, such as that figured 
in Plate X. fig. 6, these ridges are seen to contain peculiar oval masses (A, A). These 
masses presented a fine granular structure, very like that which has been described as 
characterizing the glandular tissue of Bipalium Diana and Bhynchodemus. No further 
structure could be made out in them ; but from these oval masses an irregular tract of 
similar glandular matter, disposed in elongated masses as in the skin-glands, could be 
traced up to a point a little above the testes. The oval masses and their accompanying 
glandular tracts were not to be seen in every successive vertical section, but occurred at 
slight intervals. But a satisfactory longitudinal section of the ridges could not be 
obtained in order to show the amount of separation between the gland-masses in it, or 
whether there was any regularity in their arrangement, the tissue «f the specimens of 
B. Ceres being somewhat soft. No special opening corresponding to the gland-masses 
could be detected along the line exteriorly. These organs in B. Ceres are of great 
interest, and need further investigation, which I hope that the expected arrival of a large 
number of specimens from Ceylon will permit of. It is possible that these gland-masses, 
with their accompanying tract of glandular matter, may be a foreshadowing of the 
segment-organs in Annelids, which, in the leech at least, as is well known, make their 
appearance in development as solid masses of tissue, and subsequently become hollow 
(Lettckart, loc. cit. p. 704). 
Muscular System. — Great stress has been laid by various authors on the supposed 
fact that whilst in Annelids, Nematoids, Trematodes, and, in fact, all higher worms, the 
external coat of the body was arranged circularly, and the internal longitudinally, in 
Turbellarians the reverse was the case ; and the statement has been made in such a 
form that it really appeared as if an inversion of the muscular coats must be supposed 
in order to get at the proper homological relations of the muscular structures. And 
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