294 BULLETIN 58, UNITED STATES NATIONAL MUSEUM. 



Only the type specimen of this species hem<r known, the description 

 by Boulenger is here reproduced. 



Description of type specimen. — Adult female; British Museum; 

 Formosa; R. Swinhoe, collector (fig. 256) . Head narrow and elongate ; 

 eye moderate ; rostral broader than deep, just visible from above ; inter- 

 nasals a little broader than long, shorter than the prefrontals; frontal 

 once and a half as long as broad, as long as its distance from the end 



of the snout, shorter than the parie- 

 tals; loreal as long as deep; one pre- 

 ocular and three postoculars; tempo- 

 rals 1 + 2 ; 6 supralabials, third and 

 Fig. 25fi.— natrix swinhonis. Enlarged, fourth entering eye, fifth very long; 4 

 SIDE OF HEAD COPY FROM GI7ENTHER, ^ kblals iu coutact wlth thc autC" 



Ann. Mag. N.vt. Hist., (4), 1, 1868, pl. _ . i • i i ^ • ^ 



XIX, FIG. F. rior chm-smelds which are shorter 



than the posterior; scales strongly keeled, of outer row faintly keeled, 

 in 15 rows; ventrals 150; anal divided; subcaudals circa 50. Brown 

 above, anteriorly with irregular blackish spots; occiput and nape 

 reddish, with abroad black collar; a black spot below the eye, and 

 an oblique black band on the temporal region; lower parts yellowish, 

 powdered with brown on the sides. 



Dimensions. 



mm. 



Total length 580 



Tail [defective] about 100 



Habitat. — This species is described from Formosa. Only a single 

 specimen is known, the t}^e, collected by R. Swinhoe, being in the 

 British Museum. 



Remarks. — The nearest relative of this species appears to be Natrix 

 nuclialis described in 1891 '^ by Boulenger from specimens in the Brit- 

 ish Museum, collected by A. E. Pratt at Ichang, on the upper Yangtse. 

 The scale formxula is the same, but N. nuchalis has the scales very 

 feebly keeled, a, shorter head, and a very distinct groove along the 

 middle of the back. 



Genus ACHALINUS«> Peters. 



1869. Achalinus Peters, Men. Ber. Berlin Akad. Wiss., 1869, p. 436 (type, A. 



spinalis). 

 1877. Ophielaps SauvaCxE, Bull. Soc. Pliilom. Paris (7), I, p. 108 (type, 0. bra- 



connieri). 



The statement that this genus has no postoculars is scarcely quite 

 correct. It is true that in some of the young specimens no such 

 shield can be detected, but in our large specimen, No. 34046, there is 



«Ann. Mag. Nat. Hist. (6), VII, p. 281. 

 b From a, without; ;<;aAzr65, poison fang. 



