THE CESTODA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 21 



amcsboid in appearance. The largest measure "017 mm ; the smallest noted, "012 mm. 

 There is a well-marked yolk recservoir 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 is a 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 previou.sly 

 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 Linstow is 

 •055 mm., which is considerably less than the smallest measurement observed in 

 D. scoticus. 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. (PI. I. figs. 5 and 6.) 



In Stenorhynchus leptoriyx 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. 



(ROY. SOC. KDIN. TRANS., VOL. XLVIII., 443.) 



