l82 CASTOROLOGIA. 



The brain of the beaver contains the insurmountable proof of the 

 sagacity of the animal, and shows the low mental power with which 

 it is endowed. The lowest in the scale of mammals is the " Duck- 

 billed beaver, " of Australia, (^Ornithorjnichus Paradoxus) ^hich wzs 

 described by Mr. William Sharp, in Harper's Magazine for May, 

 1890, as "an animal that is part fowl and part beaver." Next in 

 order are the Marsapials or Pouched Animals, with the Kangaroo as 

 the type ; the only example in America being the Opussum {Didcl- 

 phys Virginia7ia) , of the Southern States. The brains of both these 

 classes according to Professor Richard Owen, resemble those of birds 

 in the absence of the corpus callossum ; and the brains of the Roden- 

 tia are only one step higher. The average weight of brain to body 

 in the beaver is stated as i to 532 ; the average for the whole class 

 mammalia according to Leuret, is i to 186 ; and in man it is i to 36. 



The secretion which is contained in the castoreum glands, is un- 

 doubtedly the most peculiar distinction of the genus Castor. This 

 waxy substance, with its queer odor and questionable economy to 

 the beaver, is found in two large pockets or sacs situated near the 

 butt or base of the tail, enveloped in muscles specially fitted to en- 

 able the discharge of any portion at will. They do not appear to be 

 connected with any other organ, and are akin to the musk glands of 

 the Musquash or the civet glands of the Civet Cat ( Vivcrra Civctta). 



The following note is taken from Dunglison's Medical Dictionary 

 (1874) : — " Castor or Castoreum ; a peculiar, concrete matter found 

 in both sexes of the beaver. Odor — strong, unpleasant, peculiar. 

 Taste — bitter, subacid. Color — orange-brown. Uses — anti-spasm- 

 odic." The variation in the analyses of castoreum, constitutes one 

 of the two points of difference between the European and the Cana- 

 dian beavers. The other difference is found in a close examination 

 of the bones of the skull, which is made the grounds of a prolonged 

 controversy with tedious conflicting evidence, as it is on these two 

 points alone that the new species is based. As, however, this 

 monograph is a popular rather than a scientific treatment of the 

 subject, the details of many purely technical discussions are omitted 

 but the results of all important investigations are recorded. 



