('()LLECTIN(J AND PRKSEHVIN(J MAMMALS. 



439 



The skull is nlso to Ix; preserved. It may he cut off of the hody, 

 (lil)ped in (h^y arsenic and hung up to dry, or it may he cleaned at 

 once. To clean it, the skull nuist he hoiled till the flesh is tender 

 enough to scrajx' off. 'i'he skulls of small mannnals are delicate and 

 the first attempt to clejui them is almost certain to result in the 

 breaking of some of the small bones of the palate, if indeed, the 

 entire skull is not destroyed in removing the brain. The latter 

 operation can best be done by using a small wire with one end 

 bent at right angles to the rest and hammered flat. For scraping 

 the flesh from a sknll, a small knife will answer and a tooth brush 

 is useful in brushing away loose particles of flesh and cleaning 

 angles after most of the flesh is removed. The forceps which 

 usually accompany a dissecting set will be found useful at many 

 points in the operation. A small amount of washing soda or potash 

 boiled with the skulls makes them easier to clean, but these sub- 

 stances cause the sutures to open and must be used sparingly. Skill 

 can only be acquired by practice and it is surprising to know how 

 much longer it takes to skin and clean the skull of the first animal 

 than it does to accomplish the same work after a little practice. 



It is necessary to attach a label to both skin and skull and to give 

 them each the same number in order that their history and identity 

 may not be lost. On the label should be written the locality and 

 date of capture, the sex of the animal, the measurements and the 

 name of the collector, together with a serial number which he gives 

 to each of his specimens (Fig. 1). The date is essential because the 

 color, as well as the length and density of the hair, varies with the 

 season and two or more species have sometimes been described from 

 specimens which differed greatly in appearance because they were 

 taken at different seasons. Among some groups, the sexes differ 

 greatly in appearance and size and hence it is important to know 

 the sex of a specimen. Conventional signs are generally used on a 

 label, the Venus mirror 9 indicating a female and the sign of 

 ]\Iars a male. It is well to record in a permanent note book the 

 same data, together with other information concerning the exact 

 place and circumstances of capture or other notes of interest. 



If there is no time for skinning mammals, they can be slit open 

 and dropped into alcohol, 80 to 85 per cent., or formalin, 2 to 3 

 per cent., and treated the same as fishes or other zoological speci- 

 mens. However, the fluids extract color from the hair and dry 

 specimens are in every way better. 



Skeletons of mammals are also of value for study. To prepare 



