98 SHOULDER-GIRDLE AND BREAST-BONE. 



Blind-worm (Orvet) may be taken as the type of its own group ; and it will illustrate the fact 

 that these limbless Scincoids are the highest of the Worm-shaped Saurians, the Amphisbaenae 

 being next below them, whilst the true Ophidia lie at the base of the whole Class. 1 



In Anffuis we find three Shoulder-splints ; two cartilaginous moieties of the true Shoulder- 

 girdle, each divided into five regions, but nowhere segmented through ; and in correlation with 

 these halves there is a well-developed prse-sternum, not continuous with the ribs, and answering 

 to the lower part of the last cervical and the first thoracic arch. 



Anguis A. My youngest Blind-worm was three inches long, scarcely larger than the figure 

 given of its own clavicle (Plate VIII, fig. 2, cl.). This figure, showing also the rest of the 

 shoulder, is magnified twenty-five diameters. Besides the presence of the splints, which are so 

 profuse in the Fishes generally, but are absent in the Amphibia, we note here a deficiency of 

 proper shaft-bones, quite as great as occurs even in the Urodelous Amphibia (see 'Axototl ;' 

 Plate VIII, fig. 1). 



The upper part of the shoulder-plate of Anguis (Plate VIII, fig. 2, s. sc., sc.) is like a pruning 

 hook, the lower and much larger part (p. cr., cr., e.cr.) is not unlike a ploughshare. The anterior 

 angle of the supra-scapula is rounded off, the posterior is produced backwards and down to the 

 glenoidal region, the posterior margin is sinuously concave. The scapular neck is rather narrow, 

 and it then widens gently into the two parallel regions below. The supra-scapula is unossified, 

 and the scapula is a mere epiphysis of the coracoid (cr.). This epiphyseal bony matter is no 

 longer peripheral, as in the Anoura ; but it is subcentral, as in all the Reptilia proper ; so that 

 whenever a cloud of bone appears, there the tissue is composed of five layers besides the peri- 

 chondrium, viz. two outer and one innermost layer of nucleated cartilage-cells, and a pair of 

 subcentral layers of endosteal bone, the immediate calcification of the daughter-cells of the 

 cartilage. This condition is persistent wherever there is no ectostosis, and this description is true 

 of all the Class. The best defined morphological region is the coracoidean (cr.), for this notably 

 has undergone ectostosis, in addition to the inner calcareous growth ; but it is separated to a great 

 extent from the prae-coracoid by a large cleft, which, however, is arrested at both ends (cr. f.). 

 This is the only morphological subdivision of the plate ; it is indebted to the different histological 

 regions for the others. 



The coracoid is of the usual phalangiform shape ; but the prae-coracoid (p. cr.) is everywhere 

 broader than the neck of the coracoid ; it is continued downwards from the scapula to the epi- 

 coracoid (e. cr.), and it receives some bony matter from both regions, but has none of its own ; 

 its scapular root is the " prse-rnesoscapula," as in the Frog. We look in vain for any sign of a 

 " glenoid" cavity in Anguis, for the scapular region passes into the coracoid almost insensibly 

 (fig. 2, sc. cr.). If the ordinary nerve-passage has any existence, it is in the membranous fenestra, 

 and does not pierce the head of the coracoid, as in the Frog. The Shoulder-plate becomes one 

 again beneath the fenestra. This part the epicoracoid is a very large oblong, anteriorly hooked 

 plate, very thin, elastic, and diaphanous ; the left underlies the right to some extent. All but 

 the headlands of this large territory is occupied by feeble endosteal deposit (a coracoidean 

 epiphysis). This bony region is irregularly triradiate; a small ray ascends into the root of the 

 prse-coracoid ; another runs backwards under the coracoid ; and the largest sweeps forwards in an 

 elegantly lunate form towards the front hook of the Shoulder-plate. Loosely connected with 



1 I hope to show this fact, at some future time, in a paper on the Reptilian Skull. 



