6 
A New Leech 
The second pair is much the largest in size. The third pair is small, 
and though perhaps not functionless, may be regarded as vestigial; 
they alone did not seem to pulsate; I can offer no explanation as to 
the cause of their reduction. The vesicles are pale in colour, in fact 
almost white. 
Pigment. Under the epidermis are found large clear pigment cells 
with brownish contents, similar to those found in Calliohdella tophi'^• 
Sense Organs. There are no eyes. 
On the third of the three segments of the anal region in the middle 
of the ventral surface is a large papilla about one-third as broad at its 
summit as the segment on which it is borne and from which it projects 
posteriorly (Fig. 3). Its summit is flat and elhptical, and has no deflnite 
Fig. 3. Ganymedes cratere. Mid-ventral papilla on the third segment of the anal region 
(much enlarged). 
apertures. The papilla is found to consist of soft spongy tissue, among 
which are seen groups of elliptical cells with elongated nuclei, packed 
round one another, and resembhng in section the coats of an onion, 
recaUing the structure of a Pacinian corpuscle, or the taste buds of the 
circumvallate papillae of the mammahan tongue, or the so-called 
chromophilous “gland” of Tomopteris (which I maintain is sensory in 
function). I will not go so far as to say these cells have ciha projecting 
freely from the flat summit of the papilla, though it seems to me not 
unlikely. I consider that the function of these cells is olfactory or 
gustatory. 
Digestive System. The mouth is elliptical in outhne and situated in 
the centre of the anterior sucker. When shut it forms a longitudinal 
slit. The anus opens dorsally between the second and third segments 
of the anal region. There is an oesophageal bulb or pharynx with thick 
muscular walls. The pharyngeal sheath is reduced in length. To the 
best of my belief salivary glands are present, but I am not sure; there 
appear to be slight traces of glandular tissue in the position where one 
would expect salivary glands to be. The stomach is the longest part 
of the alimentary canal (Fig. 4). As is usual in leeches, caeca are present, 
and herein is exhibited a marked contrast to the condition in Calliohdella, 
