118 SHOULDER-GIRDLE AND BREAST-BONE. 



of interest, as compared with the instances already given ; in some respects it is still more 

 important, being the youngest Lacertian I have been able to obtain for these researches. The 

 supra- scapula (s. sc.) may be likened to a fan, or, still better, to an axe-blade, and it is not very 

 irregular in form ; the upper margin is convex, the sides concave ; these approach each other as 

 they join the top of the narrow scapula. This bone (sc) is a flattened ray, narrowest at its 

 middle, and broadest below; and having at its lower third a " meso-scapular" or acromial spur 

 growing forwards, at right angles to it (rn. sc.) : this spur is cartilaginous at its free end, 

 and is bounded above by the scapular and below by the coraco-scapular notch. This is 

 the clearest prophecy concerning the "acromion" of the Mammal, especially of the Monotreme 

 and the Cetacean, that is given forth by the Lizard group : it is a "sure word" to him who can 

 interpret it. The unossified end of this acromion of the Gecko is exactly that morsel of cartilage 

 which will be found cut off from its own stem and grafted upon the upper end of the clavicle in 

 the Bird and the Mammal, a metamorphic blending of the en do- and exo-skeletal elements never (as 

 far as I have seen) to be found in the Cold-blooded Vertebrata. 



The interspace between the scapula and the coracoid is a thick wedge of clear cartilage, the 

 bifid posterior edge of which is the glenoid cavity (gl.). Here we have another typical "coracoid;" 

 it is typical as a Lacertian coracoid, for I know of no fuller development of this morphological 

 region as to mass; in the Birds, however, although much of the anterior cartilage is absent, yet 

 in them there will be found two perfect lines of segmentation never seen in the Lizard, namely, 

 one between this bone and the scapula, and the other between the head of the coracoid and the 

 prse-coracoid. 



The splint-bones of Hemidactt/lus are intermediate between their typical condition in the 

 Iguana and L&manctus, and their aberrant flattening-out in the Cyclodonts. The curved 

 clavicles (cl.) are typically narrow and rounded above; below the curve, however, they become 

 flat, broad, and partly discontinuous ; there is a large membranous space, like that in La;manctus, 

 but larger, and their ends are squared, nearly reach each other, and have the anterior spur of the 

 " interclavicle" between them. The latter bone (i. cl.) makes a considerable approach to that of 

 Cydodus ; but the posterior bar is much the largest; the other three are delicate and spicular, the 

 lateral rays being twice as long as the anterior. The former are somewhat sigmoid, but on the 

 whole are very little curved backwards, the latter ends between the clavicles. The large hinder 

 ray is a flat sharp-edged blade, and the whole is another variety of a "dagger of lath." The 

 hinder half of the large blade underlies the Sternum, which in the glycerine preparation can be 

 clearly seen through it. In the centre of these four rays there is an elliptical membranous space, 

 which is an indication either of a once perfect division, as in Anguis (PI. VIII, fig. 2, i. cl,), or 

 at least of some symmetrical division of this splint at an earlier stage. 



The Sternum (st.) is of the typical Lacertian form, save that the costal margins are rather 

 rounded; the coracoid margins are sinuous, and the lower lip (fig. 1) is truncated behind and 

 pointed in front, whilst the opposite of this is the case in the upper coracoid lip (fig. 2). The 

 coracoid edge is thick, whilst the rest of the Sternum is thin, and rather flat ; it is deeply 

 notched in front, but all the rest has become one cartilage ; three pairs of ribs articulate with its 

 sides. 



The posterior sternal horns (figs. 1 and 2) are continuous with the fourth and fifth thoracic ribs ; 

 but they are not continuous with the posterior end of the Sternum, as in the Iguana ; this gives 

 us our fourth type of Lacertian Sternum, and two more remain for description. Certainly these 



