HEEPETOLOGY OF JAPAN. 



273 



olive (light bluish gray where the epidermis has come off), with broad 

 black crossbars on the anterior part of the back, soon breaking up 

 into four series of large squarish and alternating black spots; the 

 outlines of the dark and light colors is very ragged and the keels light 

 colored, even in the black patches as if the light color pattern had 

 been produced by scraping off the black color with a knife from an 

 uneven surface; temporal region dark, with a black line crossing ob- 

 liquely from upper postocular across anterior temporal, upper portion 

 of sixth supralabial, and middle of seventh to angle of mouth; supra- 

 labials yellowish, narrowly edged with black along the posterior 

 suture, the one below the eye on the fourth being heaviest; throat 

 yellowish, a broad band of similar color curving up behind the tem- 

 poral region so as to form a collar; lower neck yellowish, the under- 



243 



Figs. 242-243.— Natrix tigrina. IJ X nat. size. 242, top of heap; 24.S, side of head. No. 7385 



U.S.N .M. 



side gradually becoming darker posteriorly, each ventral being marked 

 basally with an increasing amount of dark slate color until the under- 

 side posteriorly is nearly uniform slaty black. 



Dimensions. 



mm. 



Total length 682 



Snout to vent 507 



Vent to tip of tail 175 



The young do not differ materially from the adults. 



Our largest specimen (No. 12711) measures about 935 mm. in total 

 length, and probably few grow to be more than 1 meter in length. 



Variation. — The scale formula of this species is fairly constant. 

 All the specimens examined and on record have 19 scale rows, a 

 divided anal (except No. 33988), and seven supralabials (two of our 

 specimens have only six on one side). Hilgendorf in a series of 40 

 found only one in which the two preoculars were fused into one, and all 

 26485— No. 58—07 18 



