1HE BRITISH REPTILES. ICX) 



about them, and can confine our attention to the two groups of far 

 greater importance, the lizards (Lacertilia) and the snakes (Ophidia). 



In the Lacertilia the branches of the lower jaw are firmly con- 

 nected by a bony suture, so that the mouth is not expansible ; the 

 nasal bones enter the border of the nasal apertures, the pterygoid 

 touches the quadrate, the vomers are distinct ; the tongue is not 

 retractile into a basal sheath. Most lizards have limbs, all of them 

 have shoulder girdle and hip girdle more or less developed, even 

 when there are no limbs ; most of them have movable eyelids and 

 external ear-openings, and have the back and sides covered with 

 overlapping scales. There are nineteen or twenty orders, with only 

 two of which Anguidae and Lacertidae we have here to deal. 



In the Anguidae the body is rigid and protected by tubuliterous 

 bony plates beneath the scales ; the scales are overlapping ; the 

 head has symmetrical shields on the upper surface, with a large 

 occipital shield at the back. The tongue is rather long, the hinder 

 part bifid and thick and covered with villose papillae, the fore part 

 emarginate and thin and covered with scaly papillae, and extrusible 

 and retractile into a fold in the villose portion. The teeth are solid, 

 and, after the first set, grow between the bases of their predecessors. 

 The premaxillary is single, the nasals distinct, the parietals single. 

 The supratemporal fossa has a bony roof. The clavicle is slender, 

 the shoulder girdle and hip girdle being always present although 

 there may be no limbs. The tail is long, brittle, and reproducible. 

 There are seven genera, some of which are viviparous; only one, 

 Angiiis, is British (Plate xxviii., 75). 



In the Lacertidae the body is not rigid and there are no bony 

 plates beneath the scales. The dorsal scales are arranged side by 

 side or overlap, and are keeled or otherwise, large or small, but 

 usually smaller than the ventrals, which are broader than long and 

 generally placed in well-marked rows. The shields of the head are 

 symmetrical, mingled with small scales, and attached to the under- 

 lying bones. The tongue is flat, long, bifid at both ends, and 

 covered with scaly papillae. The teeth are hollow at their bases, 

 and have mostly two or three cusps. The premaxillary is single, 

 the nasals distinct, the parietal single. The supratemporal fossa has 

 a bony roof, but is practically wanting, owing to the enlargement of 

 the post-frontal. The clavicle is diluted, the inter-clavicle cruciform. 

 The limbs are well developed, with five digits on each, all with 

 sharp claws. The back of the thigh is poriferous. The tail is 

 long, pointed, and brittle. The ears are exposed, so are the eyes, 

 with their round pupils and distinct lids. There are twenty genera, 

 of which only one, Lacerta, is British (Plate xxviii., 76 to 78). 



In the Ophidia the mouth is expansible owing to the branches of 

 the lower jaw being connected, not by a bony suture, but by 

 an elastic ligament. The nasal bones form a border round the 

 nasal apertures. The pterygoid, when present, is long ; it is 

 generally attached to the quadrate, and in many cases touches the 

 mandibles. The vomer is distinct. The tongue is smooth, flat, 

 and bifid, and retractile into a sheath. Tho. limbs and girdles, when 

 present, are vestigial. There are no external ears. The ev.es are 



