Tachydronius. 163 



anterior loreal above the postnasal* ; anterior loreal shorter than 

 second ; 4 upper labials, rarely 3t or 5J anterior to the subocular, 

 which is narrower beneath than above. Temporal scales moderately 

 large, rhombic or hexagonal, strongly keeled ; one, two, or three large, 

 keeled upper temporals, first very rarely§ in contact with the fourth 

 supraocular ; a long and narrow tympanic shield. 



3 pairs of chin-shields, || first or first and second in contact in the 

 middle. 15 to 24 gular scales in the median line, anterior narrow, 

 juxtaposed, more or less keeled, then increasing in size, imbricate, 

 pointed, strongly keeled, and merging gradually into the rather 

 indistinct collar, which is composed of 8 to 12 plates. 



Dorsal plates truncate and shortly mucronate behind, in 6 or 8 

 longitudinal series on the neck, 4 or 6 on the anterior part of the 

 body, 4, very rarely 6, in the middle of the body, always 4 on the 

 lumbar region.^ Ventral plates obtusely pointed and shortly mucro- 

 nate, strongly keeled, in 10 or 12 longitudinal and 21 to 28 transverse 

 series. A rather irregular series of large keeled scales borders the 

 ventrals and is separated from the dorsals by a granular area. 28 to 

 40 plates and scales round the middle of the body. Preanal plate 

 rather large, usually more or less distinctly bicarinate, with smaller 

 keeled plates on the sides. 



Upper surface of limbs with rhombic keeled scales. 1 or 2, very 

 rarely 3, femoral pores on each side.** Subdigital lamellas single or 

 partly divided, 18 to 26 under the fourth toe, usually 21 to 26. 



Caudal scales strongly keeled and mucronate, the keels forming 4 

 very strong ridges on the upper surface of the bas£j.l part ; the whorls 

 nearly equal in length, the fourth or fifth containing' 12 to 18 scales. 



* In one specimen from Saigon the posterior part of the nasal is detached 

 to form a second postnasal ; the postnasal is absent on one side in a specimen 

 from Matang. 



t On both sides in a specimen from Great Natuna and in one from Java ; 

 on one side in one from Matang and in one from Java. 



i On one side in 3 specimens from Saigon, in 2 from Tay Ninh, and in one 

 from Great Natuna. 



§ One specimen from Matang, one from Bangkok, two from Tay Ninh. 



It There are exceptions. Out of 25 specimens from Sikkim, Stoliczka found 

 4 with 4 pairs and one with 3 shields on one side and 4 on the other. Annandale 

 found 2 with 4 pairs out of 27 from the Eastern Himalayas, Assam, and Burma. 



•f There is sometimes irregularity on the two sides of the same specimens ; 

 thus in a female from Siam there are 2 plates on one side and 3 on the other in 

 the two transverse series of dorsal plates just before the middle of the body. 



** Stoliczka's statement that they vary from 3 to 6 in Sikkim specimens 

 requires confirmation. The specimens on which he based his description are 

 not in the Calcutta Mviseum, Dr. Annandale informs me. 



