length in a straight Hne from tip of nose to end of tail vertebrae, not to the 

 end of the hair, and (2) length of tail, from root to end of last vertebra. The 

 length of hind foot, from heel to end of longest toe, is often made, although 

 sometimes it is measured to the tip of the longest claw. Directions for mak- 

 ing up skins may be found in any good handbook of taxidermy or in an 

 inexpensive bulletin sold by the American Museum of Natural History in New 

 York City. The skull, cleaned by gentle boiling, should always be preserved 

 and any loose bones or teeth glued in with Duco cement or a glue of celluloid 

 scraps dissolved in acetone. In all cases the skull and skin should each bear 

 a number corresponding to a record entry of the name, sex, habitat and date 

 of capture. 



The naturalist learns to identify mammals by their bones, especially by 

 their skulls, as well as by other characters. Quite often only the bones are 

 available, as when animals have died in fields, woods, or caves and have been 

 long exposed. Frequently the den of some wild carnivore contains bones, 

 and we wish to know just what the prey was. Owl pellets — the masses of 

 regurgitated hair and bones of previous meals — often tell more about the small 

 local mammals than could be learned by several nights of trapping. Even 

 fish stomachs sometimes contain identifiable mammal bones. As an aid to 

 this study a key to mammal skulls follows the mammal key, and a few pointers 

 are given here. 



Mammal skulls differ from those of other animals in the large brain 

 case and, except for the armadillo, heterodont dentition or specialization of 

 teeth. They share with the amphibians the possession of two occipital con- 

 dyles, the processes which articulate the skull with the first segment of the 

 backbone, but differ from amphibians in the high, rounded cranium or brain 

 case. In the introductory chapter will be found a key by which the skulls of 

 the groups below mammals may usually he recognized. 



TEETH 



The teeth furnish the most important clue to identity. If a skull is 

 found, care should be taken to gather as many of the teeth as possible and to 

 avoid dislodging them from their sockets. If a skull is cleaned, the teeth 

 should be cemented into place as soon as they loosen. If the teeth are miss- 

 ing, their sockets are of some aid, and identification is still possible. The ar- 

 rangement is a clue to the orders. The front teeth are the incisors or cutting 

 teeth. In carnivores they are small in proportion to the other teeth. In rodents 

 they are very long, and often curve in almost a semicircle within the bones. 

 In rabbits, hares and pikas the upper pair have a minute pair directly behind 

 them. In the deer, antelope and cattle families there are no upper incisors, 

 merely a ridge of bone against which the lower teeth hold the grass or twigs 

 while they arc torn away. Most native bats have a gap in the front of the 



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