ON A NEW MAMMALIAN GESTODE. 1039 
| From the Procnupines or rue Zoontoaican Socinry or Lonvon, 
1914. ] 
{Published December 1914. 
Contributions to the Anatomy and Systematic Arrange- 
yy y gs 
ment of the Cestoidea. By Frank EH. Bepparp, M.A., 
D.Sce., F.R.S., F.Z.8., Prosector to the Society. 
(Text-figures 1-9.) 
XV. On A NEW GENUS AND SPECIES OF THE 
Famity AcoLEIDa. 
INDEX. Page 
Moneecocestus erethizontis, gen. et sp. 0. ........0.--00000--.2--. 1055 
T obtained a large number of examples of this new Tapeworm 
from a specimen of the Canadian ree-Porcupine, Hrethizon 
dorsatum, which died in the Society’s Gardens on May 14. From 
the comparatively short time which the host had lived in the 
Gardens (one year and two months) it would seem to be very 
possible that it was infected with the parasite before arriving in 
London, and that this Cestode is therefore an American and not 
a Kuropean genus or species. On the other hand, there are no 
facts which would render the opposite view untenable. But little 
is known of the longevity of these worms in their final hosts. 
To the naked eye, or after an inspection with a hand-lens, 
there is nothing remarkable in the worm, which, however, 
shows on a more profound anatomical examination to present 
several features of interest, of which the most important is the 
great reduction of the female efferent organs. This feature 
would seem to place it inthe family Acoleidz ; but the systematic 
position will be considered after the structure has been gone 
into. 
This species is medium sized, the examples reaching a length 
of 50 to 60 mm., or perhaps a trifle more; the greatest breadth 
is not more than just over 3 mm. When alive, the scolex end 
of the worm swayed about with considerable vivacity, which 
I have not observed to be generally the case among tapeworms, 
the movements being, as a rule, slower. 
The segments are flat and thin, and at the end of the body get 
to be rather translucent. This lack of the usual white appearance 
is not, however, due to sterility ; the very last segment in such 
examples as I examined, by means of sections, was gravid. The 
scolex is very distinct, though the body widens immediately , 
after it. There are no hooks of any kind upon either the 
rostellum or the suckers. There is, im fact, no rostellum; the 
suckers are fairly large and conspicuous. Under examination 
with a lens, the neck appeared to be quite absent and the seg- 
mentation to commence at once. There is, however, as may be 
seen 1n longitudinal sections, a very short neck where no segments 
