THE REPTILES OF OHIO 87 



series of dark blotches but these markings are small and of a shade but slight- 

 ly darker than the dorsal surface. In other specimens the pattern is more 

 developed and somewhat darker, and is suggestive of that exhibited by the 

 common water snake. However, along each side there is a grey patternless 

 area from 4 to 10 rows of scales in width which imparts to the specimen a 

 light grey lateral stripe. 



The chin and throat are the same color as the ventral surface, and the 

 top of the head the same as the dorsal. In many specimens there is a light 

 midventral area of orange or pinkish which extends from the throat to the 

 anus. Juveniles are uniform in coloration, or somewhat patterned as in the 

 adults, but they are usually paler and often with the markings slightly better 

 defined. 



Specimens examined, 413; specimens preserved, 114; specimens studied, 229. 



Intergrades. — Specimens from many of the Lake Erie islands show inter- 

 gradation with Natrix sipedon sipedon by having patterns which are interme- 

 diate between the two forms. Random crossings from the mainland to the 

 islands and from island to island must take place occasionally since the dis- 

 tances which separate the various bodies of land are not great. It is of signifi- 

 cance, however, that the farther one gets from the mainland the less evidence 

 there is of the influence of sipedon. The proportion of specimens of sipedon, 

 intergrades and typical insularum have been worked out (Conant and Clay, 

 1936) and it has been shown that intergrades are common on such islands 

 as Kelley's Island and Put-in-Bay, which lie close to the Ohio mainland, and 

 rare on the more remote Pelee Island, Ontario, the type locality for the sub- 

 species. Intergrades and more or less typical insularum occur rarely on the 

 Catawba and Marblehead peninsulas, Ottawa County, Ohio. The procedure 

 outlined by Dunn (1934) has been followed and the island populations as a 

 whole are considered as insularum. 



Range. — The islands in the western end of Lake Erie (Map 19) . Ohio 

 records are as follows: 



Erie County: Kelley's Island (TZS 103-4. 146-50, 182, 1926-31; USNM 

 40094). Ottawa County: Catawba Island (TZS 478, 1341. 1349); Green Island 

 (TZS 137); Lakeside; Lost Ballast Island (OSM 96.1-.2); Middle Bass Island 

 (TZS 2311-62); Put-in-Bay (OSM 41 — identified as Nairix fasciala er\]ihro faster 



Shaw by Morse, 1904; SL; TZS 1932; UMMZ 35852, 42811; USNM 40067-8. 

 40108, 40115, 40119); Rattlesnake Island (OC; FMNH 2544). 



Habitat and Habits. — The island water snake is abundant on most of the 

 islands of the Put-in-Bay Archipelago. Dozens of specimens were taken in a 

 very short time on many occasions and three collectors obtained 234 of them 

 in exactly four hours on June 1, 1935. 



The islands are of limestone of a more or less porous nature and bogs and 

 ponds are rare upon them. Most of the water snakes appear to be confined 

 to the edges of the islands where there is an abundance of cliffs, ledges and 

 piles of loose rocks. On these they prowl or sun themselves and under them 

 they find an abundance of hiding places; sometimes a dozen or more were dis- 

 covered under a single rock. Specimens surprised in the open attempted to 



