516 MESSRS. MIVART AND CLARKE ON THE SACRAL 



formation with the whole of the third (9) and the preaxial bifurcation (11) of the 

 second presacral nerve. The crural (15) nerve (that passing over the brim of the 

 pelvis) we found to be entirely formed by the preaxial part of the bifurcation of the 

 second, presacral, giving off, moreover, a filament to join the obturator nerve (5), which 

 has thus three roots : — 1, the filament just mentioned ; 2, the third presacral nerve ; and 

 3, the fourth presacral nerve. The disagreement between the conditions found by us 

 and those described by the authors referred to was thus less striking in Lacerta than in 

 Chamceleo. The sacral plexus was formed from the lumbo-sacral nerve (12), the first 

 presacral (21), the intersacral (29), and the first postsacral (30). 



Teius teguexin. (Plate LXVI. fig. 3.) 



A specimen of Teius teguexin was (with other specimens, as will be hereinafter 

 mentioned) most liberally placed at our disposal by Professor Plower, the Curator of the 

 Museum of the Royal College of Surgeons, from the stores of that Institution. 

 Unfortunately, in spite of its magnificent external appearance, it proved to be, internally, 

 in a state very unfavourable for dissection, while it was the first of all save one 

 examined by us. "We cannot therefore speak with confidence as to the number of nerves 

 which contributed to form the lumbar plexus ; but we did not observe that more than 

 two did so, the third (9) and part of the second (11) presacral; but we are certain that 

 three nerves contributed to the sacral plexus in addition to the lumbo-sacral nerve (12) 

 or postaxial bifurcation of the second presacral. The first postsacral (30) certainly 

 contributed to it, as well as the first presacral (21), thus differing from the conditions 

 described and figured by Professor Gegenbaur; while of the sacral roots the intersacral 

 (29), and not a presacral root, was the largest. 



Grammatophora barbata. (Plate LXVI. fig. 4.) 



This species is described by Gegenbaur 1 as only differing from his other Lizards in the 

 equality of the two branches of the bifurcating second presacral nerve. Its sacral nerve 

 therefore, according to him, is not reinforced by the first postsacral nerve. 



In our specimens we did find it so reinforced, the sciatic nerve having thus four roots, 

 of which the first presacral (21) is (as Gegenbaur says) the largest. The lumbar plexus 

 we found to be formed, not by two but by three nerves — the fourth (2), third (9), and 

 second (11) presacral, the last bifurcating, and so giving off (12) the lumbo-sacral nerve 

 (or most preaxial root of the sciatic) as well as (11) the most postaxial root of the crural ; 

 but the two last-mentioned nerves we did not find of equal size, and the lumbo-sacral was 

 the more slender. On the right side we found the three roots of the lumbar plexus all 

 unite t ogether, and then give off two branches, viz. the obturator (5) and crural (15) 

 nerves. On the left side, however, the fourth and third presacral nerves united and then 

 gave off two branches; while the preaxial bifurcation of the second presacral also 

 bifurcated, its bifurcations joining the two branches just mentioned, and then runnin°- 

 on as the obturator (5) and crural (15) nerves. 



1 L. c. p. 200. 



