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XXII.—The Cestoda of the Scottish National Antarctic Expedition. By John 
Rennie, D.Sc., and Alexander Reid, M.A., University of Aberdeen. (With 
Two Plates.) 
(MS. received May 6,1912. Read June 17,1912 Issued separately September 6, 1912.) 
The Cestode material obtained by the Scotva Expedition consisted of eight adult 
and three larvee or immature forms. Of these, one (Anchistrocephalus mucrocephalus, 
Rud.) is not Antarctic, having been obtained from the Sunfish (Orthagoriscus mola), at 
Station 107, in 39° 12’8., 53° 44’ W., on January 1, 1903. 
Of the others, only two appear to have been previously described, viz. Dibothriocephalus 
antarcticus, Baird, and Dibothriocephalus wilson, Shipley. The hosts from which the 
Cestoda of the Antarctic and sub-Antarctic regions were obtained are, with the exception 
of the Bonito,* from which a larval Tetrarhynchus was obtained, Seals and Penguins. In 
view of this fact, the number of forms obtained may be regarded as relatively large. A 
study of the species on record from Arctic Pinnipedia suggests the interesting fact that 
the two Cestode faunas are quite distinct. Hight species of Dubothriocephalus are on 
record from Pinnipedia of the Arctic regions, none of which have so far been obtained 
in the Antarctiv. The adult forms found, however, with one exception all belong to 
this genus. 
A noteworthy feature is the relatively large proportion of very small and delicate 
species of Cestoda occurring in the Pinnipedia of the Antarctic. Indeed, none of the 
forms obtained can be described as large; the maximum size is that of D. pygoscelis, 
viz. 29 cm. 
SHIPLEY has suggested with regard to the Cestoda of Ross’s Seal that, in view of the 
feebleness and variability of its dentition, it probably feeds on soft substances, and 
expresses the opinion that the plerocercoid stage probably occurs in the tissues of 
Cephalopods. Jellyfish are also mentioned, and these form part of the food of this Seal. 
With regard to Seal Cestodes in general, we note that although the parasites are 
small the infection is generally heavy, and from this it may be argued as probable that 
the intermediate hosts become infected without much difficulty. The embryos are 
extraordinarily minute, and if dissipated in the waters would probably infect drifting 
organisms, ¢.g. Jellyfish or Ctenophora, more readily than others, e.g. Fishes. On the 
other hand, Crustacea and similar organisms of scavenging habits, feeding on the feces 
of the Seals, have an even better chance of being infected, and these may provide the 
intermediate host. Beyond this it is scarcely profitable to speculate further. 
* This fish (Thynnus pelamys Linn.) it appears was found at Station 31—some distance south of the Cape Verde 
Islands—on 4th December 1902, and its parasite therefore cannot be described as Antarctic or sub-Antarctic. 
TRANS. ROY, SOC. EDIN., VOL. XLVIII, PART II. (NO. 22). 66 
