DEVELOPMENT OF THE SKELETON OF THE TUATARA. 9 
in the above-mentioned letter to ‘Nature.’ Firstly as to the rupture of the egg-shell, 
to the symmetrical ‘clean cleft” character of which we drew attention. The 
following is a drawing of the shell of one of the eggs therein referred to which ran 
the full time; and in correspondence with Prof. Dendy concerning it and our 
suggestion that it seemed to indicate that the shell-breaker may be an actual cutting- 
instrument, he has authorized us to state his own view, since formed, on opening an 
ege at Stage S, nearly ready to hatch. He observed that the moment a small 
puncture is made in the shell, that “splits of itself, very suddenly and with almost 
explosive violence, reminding one of the bursting of a seed-vessel;” and he remarks 
that it has been suggested to him that the splitting may have been assisted by 
Ruptured egg-shell of Sphenodon after the escape of the enclosed young. 
Full time. Nat. size. 
absorption of moisture from without, by the allantoic fluid!. He reverts to the analogy 
of the well-known “ Prince Rupert’s drops,” and concludes that “the function of the 
very sharp shell-breaker is probably to make the small incision ;’ and that when that 
is done, the egg, being in a condition of high tension, simply bursts open. And he is 
the more inclined to this view from having noted that the shell of an egg contained 
in sand which had been “ somewhat excessively moistened’’ prematurely burst, and 
revealed within its interior a dead embryo in an insufficiently advanced stage of 
development. 
In the afore-mentioned letter to ‘Nature’ we recorded certain details concerning 
the treatment up to the time of hatching of the eggs brought us by Mrs. Dendy. The 
three young Sphenodons which from these we successfully hatched out were kept in 
confinement in the incubator (Hearson’s, size A I.), at the temperature at which they 
were hatched—viz. 25° Centigr. They were fed upon mealworms, small earthworms, 
cockroaches, and flies, as best obtainable. For these the individual taste was 
observed to vary somewhat. One little creature exhibited a decided preference for 
mealworms, and a “ tug-of-war” for the possession of an earthworm or cockroach was 
a not unfrequent occurrence. 
* Cf. also Dendy, 99°. p. 251. 
VOL. XVI.-—PaRT I. No. 2.—February, 1901. c 
