SAURIANS, 93 
osseous suture, so that the cleft of the mouth can be dilated only 
in the usual vertical direction. Moreover, in these limbless 
Saurians we always find bones of the shoulder hidden below the 
skin, whilst no trace of them can be discovered in the true Snakes. 
The motions of some Lizards are extremely slow, whilst those of 
others are executed with very great but not lasting rapidity. 
Many of them have the power of changing their colours, which 
depends on the presence of several layers of cells loaded with 
different pigments; these layers the animal compresses by more 
or less inflating its lungs, whereby the changes in the coloration 
are effected.” 
Dr. Giinther does not follow Dr. Gray in arranging all true 
Reptiles into the two grand divisions of Shielded Reptiles ( Cataphracta) 
and Scaly Reptiles (Syuamaza) ; but he includes the Crocodilide among 
the Saurians as a first grand division of them, Hmydosauri; and the 
other Lizards constitute his second grand division of them, Lacertini. 
These latter are again primarily divisible according to the structure 
of the tongue. ‘Thus, in the series of Letoglossa, the tongue is 
elongated, forked, and exsertile, much as in the Ophidians; in that 
of Pachyglossa the tongue is short, thick, attached to the gullet, and 
is not exsertile ; and in the Vermilingues it is worm-like, club-shaped 
in front, and very exsertile. 
The various genera of Saurians which have either not a trace of 
external limbs, or have them more or less diminutive and rudimentary 
—either the usual two pairs or one pair only, and in the latter case 
sometimes the fore and sometimes the hind pair being deficient— 
are included among the Zeffog/ossa, or the series which have a forked 
and protrusile tongue ; and so far as is practicable, we will commence 
by noticing the different serpentiform genera ; only, in a classification 
which is not confessedly superficial, it will be found that the various 
snake-like Saurians appertain to several distinct natural families, 
most of the other genera belonging to which have, in sundry cases, 
limbs that are well developed. Some of them, therefore, will have to 
be noticed as the different families to which they belong are 
successively treated of; and there will yet remain the curious ser- 
pentiform family of Amphisbenide, which Dr. Gray refers to his 
grand series of Shielded Reptiles (Cataphracta). 
The same naturalist divides the Zeffog/ossa into two tribes, which ° 
he styles Getssosaura and Cyclosaura,; and, as constituting particular 
division of the former, he includes under it the family Zyphlopide. 
which Dr. Giinther refers, as we have seen, to the order of Ophidians. 
In the series of Getssosaura, the scales of the belly and (almost 
