1890.] On tli Development of the Tuatara. Io3 



species of Puffinus (P. gavius) and two species of Procellaria. This 

 has been cited in ' Nature'* as an interesting case of commensalism, 

 and it is there stated that the birds " live in holes dug out by the 

 tuataras and keep apparently on the best terms with them." It is 

 stated that the tuatara generally lives on the right and the sea-bird 

 on the left of the inner chamber. 



I believe it is quite a mistake to suppose that any friendly relation 

 whatever exists between the tuataras and the birds, and that here, 

 as in the somewhat similar case of the prairie dog and rattlesnake, 

 the idea of friendliness is quite out of place. It is true that the tuatara 

 sometimes makes use of the burrows of the mutton-bird (though I 

 have never found a tuatara living in the same burrow as a mutton- 

 bird), but it cannot be said that the two species ever live on more 

 favourable terms than those of mutual toleration. At one time I kept 

 two kiwis in a large house with a number of tuataras, and a tuatara 

 would at times shelter itself in the same box or corner as a kiwi 

 the two never attempting to fight, the tuatara hiding itself under 

 the kiwi as it would do under a stone, whilst the kiwi seemed not to 

 notice its presence. The tuatara seems to enter the burrow of the 

 mutton-bird just as it would shelter itself in any other hole in the 

 ground. 



In any case, the tuatara must be an untrustworthy associate, for 

 or four occasions I have seen or captured tuataras with young mutton- 

 birds in their mouths. It is probably a truer view of the situation 

 to suppose that the chance of getting a nestling renders the burrows 

 of the mutton-bird more attractive to the tuatara. 



Dr. Giinther, in the absence of personal observation, supposed that 

 the tuatara was incapable of burrowing. It is, however, certain that 

 it can burrow well in such light soil as is found on Karewa, and 

 even in the clay soil on which my lizard -houses are situated the 

 animals have made burrows fully two feet in length, in which they 

 are completely hidden. Not all the lizards, however, are so indus- 

 trious; most of them have contented themselves with the artificial 

 burrows, in the shape of long wooden boxes and drain pipcn, with 

 which they have been provided. 



We spent some days camping on the island and captured a number 

 of tuataras, but searched in vain for eggs, though we opened up many 

 burrows in the hope of finding them. The smallest tuatara found 

 was 4*9 inches in length. Not finding eggs, we dissected several 

 tuataras, thinking that the condition of the ovaries might tell us 

 whether we were too early or too late in the breeding season, but the 

 dissection revealed no eggs at all approaching maturity. 



We took away from the island a number of tuataras, hoping that 



* October 19, 1882. See also ' Transactions of the New Zealand Institute,' 

 Tol. 14, p. 274. 



M 2 



