212 G. A. BOULENGER ON 



I. Length from snout to vent (in millimetres). 2. Scales and plates' round middle of body. 3. 

 Longitudinal series of dorsal plates and scales. 4. Longitudinal series of ventral plates. 5. Transverse 

 series of ventral plates. 6. Plates in collar. 7. Gular scales in straight median line. 8. Femoral pores 

 on each side. 9. Lamellar scales under fourth toe. 



Habitat. South-Eastern Siberia, Manchuria, Corea. 



T. amurensis is the most Lacerta-like species of the genus, and its agreement in 

 many respects with L. vivipara [ is the more noteworthy for the fact that the latter 

 is the only species of Lacerta which extends eastward to the Pacific Ocean. 2 The 

 agreement is not only in the form of the head and the comparatively short tail, but 

 also in the shape and arrangement of the head-shields, especially those bordering the 

 nostril, and the occasional separation of the fourth supraocular from the frontoparie- 

 tal, 3 and of the ventral shields. As the scaling of the back and the coloration may 

 very well be derived from the condition in L. vivipara, I have little doubt that the 

 genus Tachydromus is to be regarded as directly modified from an oriental species of 

 Lacerta connected with L. vivipara, if not from that species itself. 



2. Tachydromus tachydromoides, Schleg. 



Lacerta tachydromoides, Schleg. Faun. Japon., Rept., p. 101, pi. i, figs. 5-7 (1838). 

 Tachydromus japonicus, Dam. et Bibr. Erp. Gen. v, p. 161 (1839) ; Giinth. Rept. Brit. Ind., 



p. 69 (1864) ; Hilgend. Sitzb. Ges. Nat. Fr. Berl., 1880, p. 112. 

 Tachysaurus japonicus, Gray, Cat. Liz., p. 52 (1845). 

 Tachydromus tachydromoides, part., Bouleng. Cat. Liz., iii, p. 5 (1887). 

 Tachydromus tachydromoides, Giinth Ann. and Mag. N.H. (6) i, 1888, p. 169 ; Stejneg. Herp. 



Japan, p. 247, fig. (1907). 

 Tachydromus holsti, Bouleng. Proc. Zool. Soc, 1894, p. y^^, pi. xlix, fig. 1. 



Body feebly depressed. Head if to if times as long as broad, its depth equal to 

 the distance between the anterior corner of the eye and the tympanum, its length 

 3§ to 4 times in length to vent in males, 4 to 4^ times in females ; snout pointed, 

 with strong canthus and nearly vertical loreal region, as long as the postocular part of 

 the head. Pileus if to 2 times as long as broad. Neck as broad as the head. The 

 hind limb reaches the axil, the shoulder, or the collar in males, the wrist, the elbow, 

 or the axil in females ; foot 1 to if times as long as the head. Tail 2 to 3f times the 

 length of head and body (if times in the very young). 



Nostril pierced between three shields. Rostral not entering the nostril, nearly 

 always in contact with the frontonasal \ usually broadly; frontonasal as long as 

 broad or slightly broader, as broad as the internarial space or a little broader ; 

 prefrontals forming a median suture ; 6 frontal as long as its distance from the end 

 of the snout, i\ to 2 times as long as broad, usually narrower behind than in front ; 

 parietals as long as broad or a little longer than broad (up to if), interparietal if to 

 2 times as long as broad ; occipital small, much shorter than the interparietal, often 



1 I have therefore represented details of that species on plate XL, VI for comparison with T. amurensis. 



i The Easternmost specimens show, on an average, a lower number of pores (5 to 11) than the Western. 



3 A character which has become fixed in T. sexlineatus, at the other end of the series. 



* Two exceptions, male from Koshikeu and female from Koyosun, in which the nasals meet behind the rostral. 



■• Sometimes separated by a small azygos shield, according to Stejneger. 



