SA URIANS. 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 thgse 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 (Sguamata) ; but he includes the Crocodilidce among 

 the Saurians as a first grand division of them, Emydosauri ; 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 Leptoglossa, 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 Leptoglossa, 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 Amphisb(znid<z, which Dr. Gray refers to his 

 grand series of Shielded Reptiles ( Cataphracta). 



The same naturalist divides the Leptoglossa into two tribes, which 

 he styles Geissosaura and Cydosaura; and, as making a particular 

 division of the former, he includes under it the family Typhlopida. 

 which Dr. Giinther refers, as we have seen, to the order of Ophidians. 

 In the series of Geissosaura, the scales of the belly and (almost 



