99 



Variety erythrogaster. Coluber erythrogaster, Shaw, 1804, 71, iii, 458; 

 Tropidonotus erythrogaster, Holbrook, 1842, 54, iv, 33, pi. 7; Nerodia 

 erytkrogader, Baird and Girard, 1853, 6, 40; Natrix fmciata erythrogaster, 

 Cope, 1892, S, 673. 



Variety tvoodhoiiseii. Nerodia woodhouseii, Baird and Girard, 1853, 6, 42. 



This widely distributed and variable species has been described under 

 a great number of names, each of which has been regarded as that of a 

 distinct species. It is doubtful if some of the above will be able to main- 

 tain their position even as recognized varieties. 



Natrix sipedon is our most common Water-snake, and when fully grown 

 attains a large size. The head is rather narrow, and pointed in front. 

 Anteorbital 1, high. Postorbitals 3. Nasal sometimes divided above. 

 Upper labials usually 8, the 6th and 7tb large, the eye over 4th and 5th. 

 Inferior labials 10. Scales strongly keeled ; arranged in 23, rarely 25, 

 rows. Ventral plates 135 to 150. Subcaudals (iO to 75. 



The ground color varies from ashy to brown. Along the back there is 

 a series of brown spots, about 30 in number, from the head to the vent. 

 These are about three scales long and descend on the sides to the 

 sixth row of scales. They are separated on the back by the length 

 of one-half scale. Along each side is another series of similarly colored 

 square blotches. These either come opposite the dorsal blotches or alter- 

 nate with them. When the three series are opposed, they unite to form 

 continuous cross bands over the body. Spaces between the lateral blotches 

 equal to or less than width of blotches. When they alternate, they touch 

 at their contiguous angles. All the blotches are dark edged, while the 

 ground color around each is paler. Occasionally the blotches unite across 

 the back to form oblique bands. Again, the ground color is sometimes 

 so dark that the blotches are obscured. Upper surface of the head brown. 

 Upper labials, lower jaw, throat, and sometimes the anterior portion of 

 the belly, yellow. The brown of the belly often takes the form of trian- 

 gular spots and these are often suffused with red. On the outer ends of 

 the ventral plates anteriorly there begin to be some mottlings of brown. 

 Further back this increases, until the whole or nearly the whole, of the 

 belly is brown. 



In the young the contrast between the ground color and spots is greater, 

 the spots .being nearly black. 



This variety of the species N. sipedon is distributed over the country 

 from the Atlantic to the Mississippi Valley, and south to the Gulf. It is 

 the common Water-snake of Indiana and it seems to be needless to specify 

 localities. 



Natrix sijiedon fasciata. This form of sipedon is characterized by 

 having a series of dorsal blotches of brown or black, about thirty in num- 

 ber to the vent, and these spots run down on the sides of the animal, 

 becoming narrower. The spaces between the blotches are occupied on 



