THE MUSKHAT. 



521 



tluMi" iKjuat ic lijihiis usually keep thciii IVoiii cultivated fields. How- 

 ever, they soiiietiiH(;s do eoiisiderable damage to ditehes, ponds and 

 railway enibanknKMits near the water by digging into the banks. 

 'i'lK^se holes are enlarged by aetion of the water, especially if there 

 is a current, and they may cause the embankment to break. Mr. 

 Hutler states that a trench of gravel through the bank or a dressing 

 of gravel or cinders on the surface of the embankment will keep 

 the animals from digging into them, and keeping them free from 

 vegetation also keep the rodents away. They are sometimes sup- 

 posed to destroy fish, but this is seldom or never the case. 



If they become troublesome, they are easily caught in traps by 

 the method previously described. It is also easy to poison them 

 with apple, turnip or cabbage poisoned with strychnine and 

 dropped near their dens. 



Synaptomys Baird, Mamm. N. America, p. 558, 1857. 



Dental Formula.— I, C, Pm, M, f^l = 16. 



Generic characters. — Form like that of Microtus, the tail being 

 shorter than in most species of that genus. Upper incisor broad, 

 with distinct grooves down their anterior faces; lower incisors 

 with the roots inside the molars; molars rootless (without prongs) ; 



Fig. 12. — Enamel pattern of molar teeth of Synaptomys : a, upper molars ; b, lower 

 molars. After Miller. N. Am. Fauna No. 12, Bureau of the Biol. Sur., U. S. 

 Dept. of Agri. 



the posterior upper one with four transverse loops differs mark- 

 edly from the corresponding tooth in any species of Microtus. 



(See fig. 12.) 



The genus is limited to North America north of the gulf states. 

 About ten species and subspecies are know^n, only one of which is 

 found in our State. 



Genus Synaptomys Baird. 



a 



b 



