PARASITES FROM THE SOCIETY'S GARDENS. 145 
which died in the Gardens on December 4th, 1911. Owing to 
its extreme resemblance to S. serrata Lss. and S. horrida (Leidy), 
I have had considerable hesitation in deciding to regard it as 
a new species. Coming, however, from such different hosts as 
the Egyptian Monitor (Varanus niloticus), Boa constrictor, and 
the present host, and from such widely separated parts of the 
world as Egypt, North America, and India, the probability is 
that they represent three distinct species. It also bears some 
resemblance to S. najw Nicoll (1912) from the Indian Cobra, 
though the length of the intestinal diverticula and the size of 
the suckers appear to be characters sufficient to separate it from 
that species. 
The length of mature specimens is 3-4 mm. and the maximum 
breadth -9-1-0 mm. just behind the ventral sucker. The cuticle 
is beset with fairly prominent spines throughout practically its 
whole extent. 
The oral sucker measures *24--28 mm. in diameter and the 
ventral sucker -28--34 mm. The latter is almost invariably 
transversely elongated, its average diameter being -29 x -°33 mm. 
The oral sucker is sometimes elongated, sometimes transverse, 
the latter being usually the case, and its average dimensions are 
°25x°26 mm. ‘The ratio of the mean diameters of the suckers is 
therefore about 5:6; it is always greater than 4:5 and never 
greater than 6:7. In S. najw and S. serrata the suckers are 
much more nearly equal. The ventral sucker is situated at a 
distance of -6--8 mm. from the anterior end of the body. The 
neck thus comprises only about one-fifth of the body-length, 
but it may be remarked that the specimens were somewhat 
contracted. 
There is no prepharynx, and the pharynx measures *17 x -13 mm. 
The esophagus is about] mm. long, and the intestinal bifur- 
‘ation takes place close in front of the ventral sucker. The 
intestinal diverticula are practically equal in length, and extend 
to a distance of *65-"9 mm. from the posterior end. The average 
in about a dozen specimens was °76 mm., which is almost exactly 
two-ninths of the body-length. They are therefore practically 
about the same length as those in S. serrata. 
The median genital aperture is immediately in front of the 
ventral sucker. ‘The cirrus-pouch just reaches the posterior 
border of the ventral sucker, and is frequently contiguous with 
the ovary. The latter is globular, with a diameter of :2 mm. 
Behind it lies the receptaculum seminis. The anterior testis, 
on the left, lies about *25 mm. from the posterior border of the 
ventral sucker, though the distance varies from -18 mm. to 
°38 mm., according to the state of contraction. The posterior 
testis, on the right, is separated from the other by a distance of 
"17 mm., though this again varies. The anterior border of the 
right testis 1s usually a little in advance of the posterior border 
of the left. 
The yolk-glands have the usual situation, almost entirely 
Proc. Zoon. Soc.—1914, No. X, 10 
