HOFFMEISTER & MOHR: ILLINOIS MAMMALS 11 



of keeping most specimens for scientific study is as dry skins, 

 fig. 4, and skulls. After a little practice, such skins can be pre- 

 pared by a simple type of taxidermy. The following suggestions 

 give some idea of the steps involved in making a collection of 

 study skins of small mammals. 



1. Assign each specimen a collection number; use this same 

 number for the skin, the skull, and any field notes or other data 

 that may have been recorded for the animal. 



2. Record in a catalog or notebook the full collecting data 

 (precise locality, date, habitat, collector) and any additional 

 notes you may wish to make. 



3. Determine the sex and take the measurements of the ani- 

 mal before starting to prepare it for a study skin or skeleton 

 and record them in the catalog or notebook ; also write them on 

 a tag (see step 6 below). Usually the measurements taken are 

 over-all or total length, length of tail, length of a hind foot, and 

 length of an ear. The head-and-body length is usually not in- 

 cluded in the standard measurements that are written on the 

 tag in the following sequence: total, tail, hind foot, ear. The 

 weight of the animal also is sometimes recorded on the tag. 



The over-all or total length is the distance from the tip of 

 the nose to the tip of the tail, not including the hair at the end 

 of the tail. Tail length is the length of this appendage, exclusive 

 of hair at the tip, when it is at a right angle to the body axis. 

 Hind foot length is the distance from the back of the heel to the 

 tip of the longest claw of a hind foot; only one foot is meas- 

 ured. Ear length is the distance from the notch of an ear to the 

 tip of the pinna or projecting part of the ear; the length of any 

 tuft or other hair is not included. Usually and preferably, meas- 

 urements are given in the metric system and in millimeters. One 

 inch is roughly equal to 25 (25.4) millimeters (written mm.) 

 and 1 foot is equal to 305 millimeters. 



4. Prepare the study skin. Make an incision down the venter 

 of the mammal from the mid-thoracic region to a point be- 

 tween the hind legs; then skin out the body, legs (to the knee or 

 elbow joints or below), and head. Remove the tail bone from the 

 sheath of skin covering it, much as you would slip an ice pick 

 from its leather holder. Carefully clean fat and grease from 

 the inside of the skin so as to prevent future staining and corro- 

 sion of the hair side. Fill the skin with a carefully fashioned, firm 

 cylinder of cotton batting designed to approximate original con- 



