716 ME. W. SATILLE KENT ON THE [NoT. 19, 



Concerning the erect bipedal method of perambulation of 

 Chlamydosaurus, it is worthy of remark that during such progress 

 the fore limbs hang lax and motionless, while the long, slender 

 tail is elevated quite clear of the ground, and, swaying slightly 

 from side to side, plays apparently an important part in preserving 

 the animal's equilibrium \ 



By experimentally tethering examples of this Lizard to light 

 cords in such a manner that they possessed full freedom of 

 action, I ascertained that they will run for a distance of at least 

 thirty or forty feet at a stretch without touching the ground wdth 

 their fore feet, and then, after resting momentarily on all fours, 

 will make a new start in the erect position, and thus continue 

 running and resting alternatively for a period of some minutes' 

 duration. Although no other existing species of lizard is known 

 to possess a similar faculty of perambulating upon its two hinder 

 limbs, it is perhaps worthy of record that I have often observed 

 of Australian species of GrammitopJiora that when running they 

 carry their heads erect in the air, at the same time sitting up, as 

 it were, on their haunches, and with the whole anterior portion of 

 their bodies raised to the greatest possible height by the full 

 extension of their anterior limbs. A similar semi-erect or " sitting- 

 up" position is also, I may observe, usually assumed by the 

 Frilled Lizard, Chlamydosaurus, when resting on the ground (see 

 rig. 2, p. 717), and when running for so short a distance 

 only as two or three yards. The progress of Chlamydosaurus 

 in its most characteristic bipedal fashion is tolerably rapid, 

 insomuch so that it was found impossible to obtain a distinct 

 photographic picture of a specimen under such conditions at a 

 distance of four or five yards with a Kodak camera having its 

 shutter working at a speed of the j^th. part of a second, and it 

 was only by enlisting the aid of an Anschutz camera with a 

 shutter set at the speed of the g-g^th part of a second that the 

 results here reproduced were secured. Even under these more 

 favourable conditions I was unable to obtain as clearly defined a 

 profile representative of the running lizard as might be desired. 

 Among those secured, however, there is one (submitted) remarkable 

 for the resemblance that the contours of the semi-erect body and 



1 Since the setting-up in type of this paper I am indebted to the Secretary for 

 a previous reference to the reported bipedal comportment of Chlamydosaurus. 

 This is made by Dr. Henry Woodward in vol. xxs. p. 13 of the Quarterly 

 Journal of the Geological Society, 1874. By a happy coincidence that accom- 

 plished geologist, in company with Dr. Giinther, overheard the comments of 

 an Australian visitor to the British Museum on a stuffed specimen in the 

 collections, and they were informed that this species habitually ran on its hind 

 legs. Dr. Woodward utilizes this and collateral evidence presented extensively 

 in his paper here quoted, which is an amplification of Prof. Huxley's essay 

 on " Animals intermediate between Birds and Eeptiles " (' Popular Science 

 E«view,' 1866), and bears practically the same title. Dr. Woodward's con- 

 cluding paragraph, to the eflPect that " the bipedal habit of the Secondary 

 Eeptiles is a peculiarity still maintained by the Australian Chlamydosaurus" 

 is of special interest with reference to the latter portion of this paper. 



