XX11 INTRODUCTION. 



then gave it a severe bite in the lip, just as this species of 

 spider usually does with any large insect which it has 

 taken. The lizard was greatly distressed, and I removed 

 the spider, and rubbed off the web, the confinement of 

 which appeared to give it great annoyance ; but in a few 

 days it died, though previously in as perfect health as its 

 companion, which lived for a long time afterwards. 



It has been already observed that the passage from the 

 Lizard tribe to the Serpents is by a succession of very 

 gradual modifications of developement. In the lower forms 

 of the Saurian group, the body becomes gradually elongated 

 and serpentiform : its ribs increase in number, the anterior 

 and posterior limbs are removed farther and farther from 

 each other, and diminish in size and power, exhibiting in 

 some forms the anterior, and in others the posterior only, 

 external to the integument, until at length they cease to 

 appear, being merely rudimentary, and wholly covered by 

 the skin. Of this transition state we have an example in 

 the common Slow- worm, Anguis fragilis, which, though 

 completely Serpentiform in its external appearance, yet 

 possesses the minute rudiments of limbs entirely concealed 

 under the integuments. Notwithstanding this general form 

 of the Serpent, they have not the expansible jaws of the 

 true Serpents : nor is the character of the ears the same, 

 the tympanic membrane not being superficial, nor the 

 auditory passage covered by integument ; the eyes, also, 

 like those of the Lizards, are furnished with moveable eye- 

 lids, which are wholly wanting in the true Serpents. 



Upon these characters, and several others of minor 

 importance, Mr. Gray founded his intermediate order of 

 Saurophidians, to comprehend all the transition forms ; 

 but it may, perhaps, be objected that the group is not suf- 

 ficiently defined to sanction such a distinction. On the 



