154 Prof. A. P. W. Thomas. | June 12, 



they would breed in captivity. Some of these were taken by Pro- 

 fessor Parker to Dunedin, a rather larger number being kept by me in 

 Auckland, as it was thought that the warmer climate of the northern 

 part of the colony would be more favourable. 



Up to the beginning of January, 1886, no eggs had been obtained 

 from my tuataras, and, as regards the lizards I then possessed, any 

 such hope was futile, for I shortly afterwards discovered that all my 

 tuataras (twenty-nine in number) were males. Thinking that our 

 visit the previous summer had been too late in the season, I deter- 

 mined to make another expedition to Karewa, this time at my own 

 expense. Professor Parker was unable to join me, owing to the great 

 distance of Dunedin from the spot ; he was, moreover, engaged in 

 working at the development of the kiwi. From this date, therefore, 

 the whole of the work fell into my hands. I spent three or four days 

 at the beginning of January in camp alone on Karewa ; but, although 

 a month earlier in the season than on the occasion of the previous 

 visit, I was again unsuccessful in procuring a single egg of the 

 tuatara. 



I made, however, a step in advance by discovering the external 

 differences between the flexes. We had been assured by those familiar 

 with the tuatara that there was no difference in the external charac- 

 ters of the sexes, and this statement seemed to be borne out by what 

 we could learn from the literature of the subject. Thus, Dr. Newman, 

 the latest writer on the subject, said* : " The males are so like the 

 females that they have not yet been distinguished with certainty." 



" The male tuatara has no special strongly marked tints, no special 

 personal attraction ; and, unlike the males of several other species 

 of lizards, are not much, if at all, bigger than the females. The 

 absence of special sexual attributes is perhaps due . . ." 



On dissecting and carefully comparing a number of tuataras, I 

 found that the current statements were not correct. There need 

 seldom be any difficulty in distinguishing the sexes ; the male is much 

 larger, and has the crests on neck and back far more strongly de- 

 veloped. In the fully adult male, the crests with their white spines 

 ai'e very conspicuous ; in the female, the crests are low, and the spines 

 are reduced to a row of white points along the back. The male, too, 

 is of more robust build, its coloration is somewhat brighter, and it is 

 more pugnacious. During the breeding season the crests in the male 

 become at times turgid and swollen, the spines standing stiffly up, 

 and giving the animal a much more antique and grotesque appear- 

 ance. It must be noted, however, that a good deal of variation 

 occurs in both the tints and brightness of colour in both sexes, and 

 the spines are larger in some females than in others. 



The discovery of the external characters of the sexes showed me 

 * ' Transactions New Zealand Institute,' vol. 10, p. 225. 



