THE CESTODA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 443 
amoeboid in appearance. The largest measure ‘017 mm. ; the smallest noted, ‘(012 mm. 
There is a well-marked yolk reservoir of pear shape between the two lobes of the 
ovary. 
The ovary in transverse section appears as an elongated band, becoming shorter and 
thicker in its more anterior parts. The larger cells measure ‘014 mm. in diameter. 
The uterus consists of a winding tube of about four loops, the limbs of which in 
transverse section are seen to wind both dorsally and ventrally. There isa large dilated 
space just at the opening. On external view, the uterus in mature segments appears 
clustered in a rounded mass posteriorly, the winding portion being distinct only in its 
more anterior region. The shelled ova vary in size; the smallest measure ‘070 x ‘043 
mm., and the largest ‘(082 x 048 mm. They are operculate. 
The testis is very large, consisting of numerous follicles occupying the greater part 
of the medullary region. The follicles are more or less spherical in form, and lie in close- 
set rows extending across the whole width of the proglottis, being separated from each 
other by the dorso-ventral muscles, which are correspondingly numerous. A common 
size of a follicle in a mature proglottis is ‘(069 to ‘087 mm. in maximum diameter. 
The cirrus sac is thick-walled, and oval in transverse section, presenting no 
distinctive peculiarities. 
From the foregoing description, it appears that this species has not been previously 
observed. From the same host, von Linstow (3) has described D. quadratus, and with 
his account a careful comparison has been made. ‘The scolex in the two species is very 
similar in general form. In D. quadratus it measures 1°3 mm. by ‘71 mm., or about 
half the dimensions of the present species. The strobila is 22°5 cm. long, and 3°5 mm. 
broad at its widest part ; the proportions of the present species are, it will be observed, 
altogether different. The longitudinal dimension of the ova given by von LinstTow is 
‘055 mm., which is considerably less than the smallest measurement observed in 
D., scotucus. The shelled ova are in D. quadratus described as non-operculate ; in 
the present species they are clearly operculate. Further, the appearance of the yolk 
follicles is quite different in the two species. 
A comparison has also been made with other Dibothriocephalus species recorded 
in Pinnipedia, with like negative results. 
In honour of the Scottish Expedition, we have named this new species Dibothrio- 
cephalus scoticus. 
Dibothriocephalus coatsi, n. sp. (Pl. I. figs. 5 and 6.) 
In Stenorhynchus leptonyx there occurred along with Bothriocephalus scoticus a 
number of specimens of a small, hitherto unrecorded Cestode. 
The total length of strobila of the examples found is from 42 to 80 mm. In a 
specimen of 42 mm. the width at the broadest part, which is 23 mm. from the 
anterior end, is 1°8 mm. 
