156 ZOOTOMV. 



of the species, many of them receiving distinctive names. 

 Along the ventral edge of the thigh is a row of apertures 

 (pori femorales) of a series of cutaneous glands. 



The genus Lacerta is distinguished from Zootoca by the following 

 characteristics : Lacerta is oviparous ; it has two small posterior nasal 

 scales bounding the nostril behind, and teeth on the palate. Zootoca is 

 viviparous, it has only one posterior nasal scale, and no palatine teeth. 



The colouring of the three species is also characteristic. Lacerta 

 viridis is either green or bluish-green, lighter beneath, more or less 

 extensively marbled with black, and sometimes having either white 

 spots, or one or two white streaks on each side. Lacerta agilis 

 is brown above with black spots, gr^en on the sides, and white beneath. 

 Zootoca vivipara is olive above, \\ith a white-edtjed blackish streak on 

 each side and a central black streak ; the ventral surface is orange and 

 blue (in summer) spotted with black. 



XIV. Place the animal in the supine position (ventral 

 surface upwards), and make a median incision 

 through the skin from the chin to the anterior 

 border of the vent : carefully separate the skin from 

 the underlying muscles and reflect it right and left ; 

 this is a matter requiring considerable care, 

 especially in a fresh specimen, since some of the 

 muscles are inserted into the ventral scales ( 124) 

 and are with difficulty separated from them : the 

 rectus lateralis ( 125) is almost certain to be 

 reflected with the skin. Note 



125. The rectus abdominis (Fig. 39, r.r, r.l, r.i), a 

 longitudinal paired muscle which, with its fellow of the 

 opposite side, forms the median ventral portion of the 

 muscular body wall. It is divided by transverse fibrous 

 bands, or inscriptiones tendinese, into segments, the 

 longitudinal fibres of which are inserted into the anterior 



o 



edges of the median ventral scales. 



The rectus abdominis consists of three portions : a ventral portion 

 (rectus ventralis, r.v) arising from the last sternal rib and inserted into 

 the ischium : an external portion (rectus lateralis, r.l) beginning as a 

 thin sheet of fibres between the skin and the pectoral muscle ( 127) 



