REPTILES. 117 



"outgrowths " or spurs (p. cr., m. cr.), exactly the counterpart of those spurs which embrace the 

 " middle pectoral muscle " of the Bird, just where it is attenuating into its narrow humeral 

 tendon. The band of cartilage, which is continuous, in front, with these spurs in Monitor 

 dractsna, is the generalised mass out of which three distinct segments are formed in the Bird. 

 The main ray of the coracoid in this Lizard is (see fig. 9) about twice the size of each of its two 

 secondary rays ; the fenestra (u. c. f.) between the two upper rays is twice the size of that 

 (1. c. f.) which intervenes between the " meso-coracoid " and the main piece. As in the Iguana 

 (Plate IX, fig. 1, e. cr.) the epicoracoid is only ossified up to the antero-inferior angle of the main 

 coracoid ; and this structure throws light upon the apparently anomalous anterior position of the 

 epicoracoid in the Monotremes ; in these, the coracoid and epicoracoid are both perfect shaft- 

 bones, and the earlier development of the coracoid proper causes a complete ossification of the 

 postero-iuferior part from the main bone. 



The splint-bones are still more delicate than in the last species ; they are, indeed, like 

 spicules rather than bones. The clavicle (fig. 9, cl.) reaches a little higher than in the last, 

 and its bend is higher up, the rounded angle of the clavicle being exactly where the arms of the 

 inter-clavicle ends, and these arms are longer relatively in Monitor than in Psammosaurus. 



The arms of the inter-clavicle (figs. 9 and 10, i. cl.) do not curve so far backwards in the 

 the former as in the latter ; and in this Monitor the longitudinal bar does not flatten out so much 

 as in the African kind ; it also reaches further back (see fig. 10, as compared with fig. 8). 



The Sternum of Monitor dractena differs in nothing important from that of Psammosaurus; 

 and one description may serve for both ; but the first pair of thoracic ribs belong to the ninth 

 vertebra, and not to the tenth, as in Psammosaurus ; also I find only two pairs of free cervical 

 ribs in this kind of Varanian. The "costa intermedia" is more obscurely seen than in the 

 last instance (figs. 9 and 10, i. r.) ; and the articular pedicle connecting the main Sternum with 

 its horns (figs. 9 and 10, st., x. st.) is shorter; the ribs (figs. 9 and 10) are thicker, relatively, 

 than in the Ouaran. 



Example 1. Hemidactylus ? 



My next illustration is from dissections of a young Gecko from Barbadoes, a little more than 

 an inch in length, and evidently, from its softness, very young. Plate XIII, figs. 1 and 2, show 

 the Shoulder-girdle and Sternum of this Lizard, magnified fifteen diameters, and drawn as spread 

 out under the " compressorium ;" this dissection being seen as a transparent microscopic object. 



In fig. 1 the lower view is given, in fig. 2 the upper; the former best displaying the 

 splints, the latter allowing the best sight of the cartilaginous headlands to the bony parts 

 of the Shoulder-girdle. In this early stage the cartilaginous parts are wholly unossified, and the 

 only bony matter seen belongs to the thin splints, and to the scapular and coracoid " ectosteal" 

 sheaths ; within these latter deposits there may be some " endosteal" bone ; but if so, it had 

 only just commenced. Even the splint-bones themselves are only partially consolidated, for I 

 found inside them copious collections of delicate connective-tissue-cells, many of which were thin- 

 walled sphserules. 1 So much for the histology ; morphologically, this specimen abates not one jot 



1 At first, I mistook these cells for thin- walled or simple cartilage-cells and hence arose the 

 error in my "Abstract" (' Zool. Proc.,' 1864, p. 341), where the true clavicle of the Lizard is 

 confounded with the so-called clavicle of the Frog. 



