21 



The sex of the specimen may be ascertained after sliinning, by 

 making an incision in the side near the vertebrae, and exposing the 

 inside surface of the " small of the back." The generative organs 

 will be found tightly bound to this region (nearly opposite to the 

 last ribs), and separating it from the intestines. The testicle»ot 

 the male will be observed as two spheroidal or ellipsoidal whitish 

 bodies, varying with the season and species, from the size of a pin's 

 head to that of a hazel-nut. The ovaries of the female, consisting 

 of a flattened mass of spheres, variable in size with the season, will 

 be found in the same region. 



Some writers advise a very careful cleaning out of the sknll, 

 ■without cutting away any of the bones, so that the skin, if other- 

 wise useless, will at any time furnish a skull for the osteological 

 series. This, however, requires so much more time, that it can 

 scarcely be done on a journey, and a skull can generally be better 

 obtained from another specimen, too much shot, perhaps, to be 

 skinned. 



The breast bone with its attachments, of at least one specimen 

 of each species, should be cleaned and preserved. 



For transportation, each skin of mammals as well as of birds 

 should, when possible, be wrapped in paper, or else arranged in 

 trays lined with cotton, and the interstices filled with the same 

 material. 



2. MAMMALS. 



The mode of preparing mammals is precisely the same as for 

 birds, in all its general features. Care should be taken not to 

 make too large an incision along the abdomen. The principal 

 difficulty will be experienced in skinning the tail. To effect this, 

 pass the slipknot of a piece of strong twine over the severed end 

 of the tail, and, fastening the vertebrae firmly to some support, pull 

 the twine towards the tip until the skin is forced off. Should the 

 animal be large, and an abundance of preservative not at hand, 

 the skin may remain inverted. In all cases, it should be tho- 

 roughly and rapidly dried. Further remarks on this subject will 

 be found in the introductory chapter. 



The tails of some mammals cannot be skinned as directed above. 

 This is particularly the case with beavers, opossums, and those 

 species which use their tail for prehension or locomotion. Here 

 the tail is usually supplied with numerous tendinous muscles, which 



