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Notes on Parastres Founp in F'RoGS IN THE VICINITY OF 
St. Paun, Minn. 
By H. L. OSBORN. 
(Abstract. ) 
Our knowledge of the parasites of even the commonest animals is very 
incomplete. Examinations of all the organs and at all seasons of the year 
and extended-over a period of several years have never been made except, 
possibly, for a few of the domesticated animals where the information 
possessed an evident and immediate utilitarian bearing. Such studies of a. 
number of common and abundant animals are much to be desired. If a 
body of such information were available it would be of great service to 
students of the trematodes and very likely make it possible to complete 
many life histories, only fragments of which are known at the present 
time. The present paper is a first step in an attempt to do this with refer- 
ence to the common frogs in the neighborhood of St. Paul. Twenty-one 
frogs were examined in June, seven in September and nine in November. 
These numbers are found to be too small for anything but a preliminary 
survey of the ground and larger numbers will be examined next year. 
The walls of the ccelom, particularly in the dorsal and anterior regions, 
are infected by nearly mature encysted individuals of Clinostomum mar- 
ginatum, Rud. This form has been reported hitherto only from fish and 
fish-eating birds. The pericardial cavity, especially in frogs during June, 
was found to contain oval cysts, sometimes grouped in masses, each cyst 
containing a distome so immature that its generic affinities cannot be de- 
termined from the data furnished by a study of its structure. It may 
turn out to be a missing early stage of some trematode whose later stages 
are already known. ‘The urinary bladder in a considerable fraction of the 
frogs examined harbors a species much like, if it is not identical with, 
the Gorgodeda attenuata which Stafford has described from a similar loca- 
tion in the frogs of Canada. A member of the Amphistomidze occurs ocea- 
sionally in the urinary bladder but is more characteristically a parasite 
of the rectum, where it is found at all seasons. In one instance Cephalo- 
gonimus was found in the rectum and small intestines. In a few cases a 
