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Cestode Genus Oochoristica 
described. While the forms from mammals have received more attention, 
much confusion exists as to the limits of the genus, and it is by the study of 
the reptilian forms that clearer light seems most likely to be shed upon the 
question, since the type-species is a reptilian and not a mammalian parasite. 
OOCHORISTICA ZONURI, sp. n. 
Host: Zonurus tropidosternum. Portuguese East Africa. 
External features. 
This is a rather large, stout worm, measuring, in a somewhat contracted 
condition, up to 102 mm. in length. The maximum width is about 3 mm. The 
strobila is irregularly contracted, and the cuticle much wrinkled, forming deep 
folds between the segments. The outline of the latter is irregular in conse¬ 
quence, as is indicated in PI. XXI, fig. 2. The hinder borders of the segments, 
as seems to be characteristic of the genus, do not overlap the succeeding seg¬ 
ments, the division between the segments being marked externally only by a 
fold in the cuticle. 
The scolex (PI. XXI, fig. 1) measures 0*9 mm. across, and is not clearly 
marked off from the strobila. There is no trace of a rostellum. The large 
suckers are oval in shape, their longest diameter being antero-posterior. The 
outside measurements of the suckers are 0-5 mm. x 0-35 mm. The aperture 
of each sucker is a longitudinal slit. 
The neck widens out to 1*5 mm. close behind the scolex. Owing to its con¬ 
tracted and wrinkled condition it is difficult to make out where segmentation 
begins. The segments are for the most part much broader than long; their 
length increases, however, relatively to their width, on passing backwards, 
and the gravid segments near the posterior end are nearly square. The genital 
pores are irregularly alternating, and situated well towards the front of the 
segment. 
Internal structure of the Strobila. 
In a transverse section (PI. XXI, fig. 3) the medullary parenchyme is seen to 
occupy a little more than one-third of the whole dorso-ventral diameter, i.e., 
the cortical parenchyme, subcuticular layer and cuticle are together thinner 
than the medulla. The cuticle is thick, and consists of two layers (PI. XXI, 
fig. 5, C l9 C 2 ). The subcuticular layer contains many curious flask-shaped 
cells suggesting mucus-cells (PL XXI, fig. 5, G.). The inner ends of these often 
project beyond the other cells of the subcuticular layer into the cortical 
parenchyme. The parenchyme, both of cortex and medulla, is loose and con¬ 
tains very few nuclei. 
Musculature. The longitudinal muscles consist of a single row of about 
40 bundles dorsally, and 40 ventrallv (PI. XXI, fig. 3, L.). Each bundle 
contains about 15 to 20 fibres of various thicknesses. Immediately underlying 
the longitudinal muscles are a few fine transverse fibres (PL XXI, fig. 3, Tr.) 
