A CONTRIBUTION TO THE ANATOMY AND 
EMBRYOLOGY OF CLADORCHIS (STICHOR- 
CHIS) SUBTRIQUETRUS RUDOLPHI, 1814 
(FISCHOEDER, 1901). 
By FRED D. WEIDMAN, M.D. 
{From the Laboratory of Comparative Pathology of the Philadelphia 
Zoological Garden and the McManes Laboratory of Pathology, Uni¬ 
versity of Pennsylvania, Philadelphia, Pa.) 
(With Plate V and 2 Text-figures.) 
In 1814 Rudolphi described, under the name of Amphistomum 
subtriquetrum, a fluke from the caecum of the European beaver ( Castor 
fiber). Little of importance was added for many years; i.e., until 
1897, when Otto described it somewhat fully including its internal 
anatomy, and 1901 and 1903, when Fischoeder wrote of it in his classical 
revision of the Amphistomidae. In 1914 Duff described a similar 
parasite, this time from the American beaver ( Castor fiber canadensis) 
which she believes to be identical with that of the European animal. 
The present communication is offered in spite of the several pre¬ 
ceding descriptions, first, because all of my material was immature 
and hence of some value from a developmental standpoint; second, 
because a wax reconstruction of the internal anatomy was made, 
allowing enlarged representation in toto with photographic accuracy; 
and thirdly, because previous descriptions could be collated with mine 
to give a fuller description than any yet published. 
My material was obtained at autopsy from the caecum of Castor 
fiber canadensis dying on June 9, 1913, in the Philadelphia Zoological 
Garden with acute haemorrhagic enteritis ( P.Z.G. 2936; U.P. Path. 
Hist. 4366). Although a careful search was made with the aid of a 
fine sieve, but eleven specimens were obtained, lying in the semifluid 
caecal contents, close to but not attached to the mucosa, which, contrary 
