HERPYLLOBIUS AllCTICUS. 
387 
and H. crassirostris (Sars). In this paper Levinsen also 
dealt with the different tlieories concerning the significance 
of the portion of the parasite inside the worm, and gave a 
concise account of his own observations on the subject. 
Giard and Bonnier (2) in 1893 published the results of 
their observations on S p h ter o n e 1 la, and suggested including 
the Herpyllobiinte as a sub-family equivalent to the Choiiios- 
toniatinae, under the heading of Sphaeronellidae. This classi- 
fication was not acceptable to Hansen (4), who criticised 
their conclusions in his work on the Choniostomatidae, and 
objected to Herpyllobius being linked with that family 
oil the grounds of extreme structural differences exhibited 
by the two forms. 
In 1900 Jensen published an account of Herpyllobius 
and Rhizorhina (6), and later on in the same year Hansen 
(5) wrote a paper on the same subject. Both these observers 
were able to make a minute investigation of these forms, with 
the result that their structure was worked out with greater 
detail than had before been possible. 
^As will be seen from this short account of the literature 
on Herpyllobius, almost all that has been written on the 
subject is in Danish, and hence not easily available. In the 
summer of 1911 Mr. F. A. Potts, of 'I’rinity Hall, Cambridge, 
(•ollected some specimens of this interesting parasite from 
Dejiarture Bay (Vancouver Island), Victoria, and San Juan 
Island, in Puget Sound, and on his return to England very 
kindly gave them to me to describe. This provided me with 
opportunity of writing an account of the animal in what I 
trust may be a more accessible form for English readers 
than at present exists. 
I sliould like here to thank Mr. Potts for the help he has 
given me in writing this paper, and also Mr. H. M. 
Chadwick, of Clare College, and Miss Lehmann, of Newnham 
College, Cambridge, for their assistance in translating the 
Danish papers, a, ml to acknowledge the hindness of Dr. H. J. 
Hausen in sending me his paper on Herpyllobius, and of 
Dr. W. T. Caiman in reading my proofs. 
