ISO RODENTIA. 



four inches; by a strong muscle in the skin, those of the back, 

 when the animal is irritated, are erected and extended in various 

 directions ; the tail is also erected, and by a quite sudden move- 

 ment, he is enabled to strike, leaving the loosened spines in the 

 body of his assailant. The flesh of the Porcupine resembles 

 young pork, and is by the Indians very highly esteemed. Spines 

 dyed of various colors, form ornaments for their dresses. (De 

 Kay.) 



6th. THE MICE FAMILY. 



Murida, (Gr. (tvg, mus, a mouse.) 



This numerous family have in each jaw, besides the two cut- 

 ting teeth common to the Rodentia, six molars (usually) in each 

 jaw, surmounted by blunt tubercles. The teeth of the upper 

 jaw shelve backwards ; those of the lower, forwards ; the feet 

 are neither webbed nor fringed with stiff hairs, but several spe- 

 cies swim with much ease. The tail is round, usually naked or 

 thinly haired. Most of this family are small burrowing ani- 

 mals ; some genera are furnished with cheek pouches. Dr. De 

 Kay, (N. H. S. N. Y.,) arranges all into two groups, I. those 

 having, II. those not having cheek pouches. The ordinary food 

 of these animals is grain, seeds, and other farinaceous matter, 

 for bruising which their teeth are well fitted ; but they .are really 

 omnivorous. 



Musdecumanus, (Lat. tenth.) The NORWAY or BROWN RAT is 

 of a grayish brown color above and white beneath ; in length, 

 from the head to the end of the tail, about twenty inches, having 

 the tail quite as long as the body. It was originally introduced 

 into Europe from the southern parts of Asia ; from its superior 

 strength and ferocity, has in some places almost entirely expelled 

 the Black Rat, (M. rattus.) It came to the United States with 

 the foreign mercenaries during the war of the Revolution, and 

 is now spread over the United States and Canadas. It infests 

 wharves and has been called the WHARF RAT, or DOCK RAT ; the 

 name decumanus alludes to the tithe or tenth of everything taken 

 by this voracious creature. 



M. musculus, (Lat. dim.) The COMMON MOUSE is of a dusky 

 gray color, has ears about half the length of the head, a long, 

 bare and scaly tail, and in constitution and disposition is similar 

 to the rat. It breeds at various seasons of the year, from six to 

 ten at a litter ; is omnivorous, but prefers vegetable food. The 

 young are, in about a fortnight, strong .enough to collect their 

 own food. The mouse is said to be very susceptible to the 

 power of music. An anecdote is related of a gentleman who was 

 playing a violin, seeing a mouse run along the floor and jump 

 about as if distracted. He continued the strain, and after some 



