OF THE NEWT, FEOGr, SLOWWOEM, AND GrEEEN LIZAED. 
287 
so careful and skilled an observer, inasmuch as I am convinced that the facts can hardly 
be made out without studying hardened sections, a method of manipulation not, I 
believe, in this instance practised by him. 
A few years subsequently Letdig (who appears to have overlooked Dr. Beale’s paper) 
published, in the ‘Archivf. Naturgeschichte’ (1867), an account of the development of the 
teeth of the Salamander, in which he arrives at conclusions very similar. He believes 
that the tooth develops in a sac which is a purely epithelial formation, and that the tooth- 
papilla, and hence the whole tooth, is entirely epithelial. The figures which he gives are, 
however, far from being accurate representations of what takes place in the newt ; but I 
have been so unfortunate as to fail in procuring a fresh salamander this summer. Santi 
Sikena (Centralblatt f. d. med. Wiss. No. 48, 1870) gives a brief account of an examina- 
tion of some Batrachians and Reptiles ; but there are no figures, and the descriptions are 
too short to be very definite. Grouping the Frogs and Lizards together, he states there 
are no marked differences to be noted from the process as known in Mammalia, save that 
the teeth become attached to the bone by the ossification of the tooth-sac ; he contrasts 
the development of the frog’s tooth, which takes place in a special sac, with that of the 
newt, which he states to be developed freely* in the mucous membrane. 
The newt ( Triton cristatus ) being in some particulars easier to study than the 
other creatures examined, I will commence the description of my own observations 
upon it. 
The teeth, examined without any prior treatment with acids, are seen to terminate in 
two unequal cusps f, sharply pointed, strongly refractive, and of a clear brownish yellow 
colour, which recalls that of many rodent incisors (Plate 46. fig. 9). This thin yellowish 
cap is so hard and brittle that it is frequently splintered by the pressure of the covering- 
glass, and is always lost when the tooth is rubbed down to reduce it in thickness, as it 
easily breaks off bodily. 
This enamel cap disappears altogether in decalcified sections, in which, therefore, the 
bifid character of the tip of the tooth becomes quite inconspicuous. 
The teeth are but feebly attached, by anchylosis of the outer side of their bases, to a 
parapet of bone (fig. 1), the enamel-tipped apex of the tooth alone projecting above 
the level of the epithelium. The inner side of the base of the tooth descends to a much 
lower level, and either tapers to a thin edge, or is actually attached to a slight elevation 
of the bone (fig. 2). 
The epithelium closely embraces the tooth on all sides where it emerges from it, 
forming a plane surface ; and there is neither groove nor fissure in which the successional 
teeth are developed, as had been generally supposed (figs. 1 & 3). 
In the place of the supposed groove there is, immediately to the inner side of the 
tooth and its supporting parapet of bone, a region which, to facilitate description, I will 
* “ Bei Siredon nnd Triton geht die Entwickelung der Zahne frei in der Schleimhaut vor sich ; beim Frosche 
dagegen in einem Zahnsakchen.” 
f This bifid termination of the tootb was noted, I believe for the first time, by Leydig. 
2 q 2 
