ART. 19 GREEN PIT VIPEE PROM CHINA STEJNEGER O 



specimens. In these the internasals are in contact in all but 5 speci- 

 mens, 4 from Siam and 1 from Tenasserim. In these, one small scale 

 is intercalated between the internasals. These, however, are in every 

 instance relatively very large, so much larger than in the series of 

 the northern form that a confusion with the latter in this particular 

 is out of the question. 



We thus find that the available material of 65 specimens falls into 

 two groups according to the size of the internasals and their contact 

 or separation by intervening scales, inasmuch as about 97 per cent 

 of the northern and highland form have small internasals separated 

 by intervening scales, while in the southern and lowland form 80 

 per cent have the large internasals broadly in contact and 20 per cent 

 have them narrowly separated by a single small scale. 



2. FUSION OF THE NASAL SHIELD WITH THE FIRST SUPRALABIAL 

 OR THEIR SEPARATION BY SUTURE 



The fusion of the nasal with the first supralabial is a rather ex- 

 ceptional condition in snakes. It is therefore, perhaps, not surprising 

 that in the same series of 34 northern and highland specimens, in- 

 cluding those from central Yunnan mentioned under the first head- 

 ing, we find only one exception to the rule that the nasal and the first 

 supralabial form distinct shields separated by a suture. This excep- 

 tion is the same specimen from Darjeeling, in the Himalayas, which 

 was also exceptional in having the internasals in contact. 



The southern and lowland series, on the other hand, is not so 

 uniform. Of the 32 specimens recorded, 26 specimens have the nasal 

 and the first supralabial fused (in 1, from Cambodia, only partly 

 so) while in 6 they are entirely separated by a suture. 



Consequently, the 66 specimens again fall into two groups with 

 relation to the fusion of the nasal with the first supralabial, inas- 

 much as about 97 per cent of the northern and highland form have 

 the two shields separate, while in 77 per cent of the southern and 

 lowland form the two shields are fused into one. 



3. PRESENCE OR ABSENCE OF ONE OR MORE SCALES BETWEEN THE 

 NASAL AND THE SHIELD BORDERING THE PIT ANTERIORLY 



In the genus Trimeresurus the shield bordering the pit anteriorly 

 is usually fused with the second supralabial into one shield. This 

 shield may be in direct and broad contact with the nasal without 

 any scale between them, or they may be wholly or partly separated 

 by one or two small narrow scales, of which the upper is usually the 

 larger when two are present. Sometimes they are reduced in size to 

 mere granules. 



