REPTILES. 99 



these overlapping, squamous Shoulder-plates, we see a pair of sigmoid rods, thoroughly ossified, 

 and quite unlike the structures they undergird; these are the clavicles (cl.), equally like those of 

 an Eel and those of a Man. Like the clavicles of an Eel, and unlike those of a Man, these are 

 pure splints (subcutaneous exoskeletal bones) ; and Duges, in his work on the Batrachians, has 

 wrongly figured these bones with a knob of cartilage on the lower end (see his plate iii, fig. 27, 

 No. 33). Nature has evidently set these clavicles here as a landmark to anatomists in their long 

 morphological journey from the worm-like Eel to the highest of the Mammalia ; and the continuity 

 of the whole clavicular series is thus clearly revealed. The backward curve of these bones is very 

 elegant, and the whole form is " a line of beauty and grace," looking as though the same fingers 

 had bent them as those which moulded our own collar-bones. The other splint, the interclavide 

 (i. cl.), is strapped on to the antero-inferior part of the prse-sternum, occupying its primordial 

 fissure, and is at present composed of two pairs of bone, one hammer-shaped and the other drop- 

 shaped, but both soon to melt into one nodule. Plate VIII, fig. 3, i. cl., shows these two 

 symmetrical nuclei as magnified 125 diameters ; they are seen from below, and lie in loose areolar 

 tissue in the gap between the front edges of the sternum. 



Above the Ganoid Fishes, this is the only instance I can give at present of the primordial 

 symmetry of the inter-clavicle ; but a careful study of the development of this bone in embryo 

 Lizards would, very probably, show it to be not at all rare. No one could have better described 

 the difference between this bone and the Sternum than Rathke, and yet he always calls it the 

 " anterior sternal bone." Nearly every other anatomist, however, has made the same mistake, and 

 the inter-clavicle has for along time past "blinded the eyes of the wise." 



The true Sternum of the youngest Blind-worm (Plate VIII, fig. 2, st.) only answers to the 

 anterior half of the first division of that of Chirotes (fig. 8, p. st.), and belongs therefore to the 

 last cervical vertebra. The two halves, the right being the largest, are united behind by a narrow 

 isthmus, but are separated by a large primordial notch in front ; each piece is pear-shaped, and the 

 broad ends come to the mid-line. The oblique anterior margins are grooved for the epicoracoids 

 (e. cr.), and the posterior free margin is continuous, and is as though it had been gnawed. Each 

 moiety has its own internal double bone-plates, which shine through the clear, compound- 

 celled cartilage ; these right and left sternal bones are bordered by a rather wide margin of 

 soft cartilage. 



Anguis B. My next specimen was three inches ten and a half lines in length ; half its 

 Shoulder-girdle is shown in Plate VIII, fig. 4, magnified twenty-five diameters, and seen from 

 without. Here the scapular bone-substance, which was bifurcate on the right side in the last, is 

 creeping upwards as a trilobate plate. The coracoid (cr.) is thicker throughout; but the 

 epicoracoid bony plate is less in proportion to the cartilage than in the last : the clavicle (cl.) is 

 very much thicker; it reaches, as is usual in the Reptilia, to the supra-scapula above, and beyond 

 the prse-epicoracoid angle below; any one who has studied the Shoulder-splints in Fishes will see 

 no difficulty in this. 



Anguis C. The next Blind-worm was almost full-grown ; figure 5 shows its two Shoulder- 

 plates seen from above, and magnified fifteen diameters. The prse-coracoid band (p. cr.) is only 

 well seen in this figure, and the difference of the right and left sides as to bony growth is made 

 manifest; for on the left side the meso-prse-scapular bone grows towards the prse-epicoracoid ; 

 whilst on the right side these patches do not approximate, and there is a quite distinct lower prse- 

 coracoid patch. This bony centre, with its circumambient cartilage, is the large, generalised 



