60 SHOULDER-GIRDLE AND BREAST-BONE. 



(Plate IV, figs. 2 and 3). Here the supra-scapula (s. sc.) is somewhat fan-shaped, with the 

 anterior angle sharp, whilst the posterior angle is rounded. The scapula (sc.) is relatively 

 broader than in Proteus, but is similarly arrested at both ends. I can see no glenoid fenestra in 

 this preparation, and the nerve-passage is large and distinct, about a line behind the end of the 

 great coracoid notch. 



The prse-coracoid (p. cr.) is relatively somewhat longer than in the Proteus, and the epi- 

 coracoid (e. cr.) is rather notched in the middle of its free margin. 



Example 3. Menopoma alleghaniensis, Harlan. 



My figure of the Shoulder-girdle and Sternum of this North-American Amphibian is partly 

 from Professor Hyrtl's dry preparation of a young male, and is partly also copied from plate v, 

 fig. 2, of his valuable work on Cryptobranchus ; it is shown as magnified two diameters. The 

 supra-scapula (Plate III, fig. 4, s. sc.), is of a less elegant shape than in the Menobranchus, and 

 the scapula (sc.) is more ossified ; partly affecting the glenoid cavity, above. I am not aware 

 if there be a glenoid fenestra ; but at any rate the nerve-passage is quite distinct. The wholly 

 unossified prae-coracoid and coraco-epicoracoid differ from their counterparts in the last species 

 by their rounded contour, and the former flap (p. cr.) is relatively shorter and broader ; the free 

 margin of the epi-coracoid (e. cr.) is sinuous. 



This is my first instance of a Sternum (st.), but as the next two instances will show that part 

 better I shall describe them more at length. This figure (from Hyrtl), shows, however, the thick 

 inner lips of the coracoid grooves, the grooves themselves, the scooped inner face of the Sternum in 

 relation with the pericardium in the fresh specimen, and the emarginate, abrupt, posterior margin, 

 with no meso-xiphisternal rudiment, such as we shall soon have to describe ; the whole of this 

 protosternum is the counterpart of the "manubrium" or " pra3-sternum " of Man and the other 

 Mammals. This little cartilage is primarily double, and belongs to the first dorsal vertebra, and 

 perhaps also to the last cervical; and the non-development of the greater part of each costal arch, 

 laterally, does not altogether prevent the out-cropping of a portion of the inverted keystone, which 

 in the air-breathing Vertebrates is so constant a correlate of the Shoulder-girdle. The visceral 

 laininaa as they approach may be thick or thin, according to what may be developed in 

 them ; but when the Shoulder- girdle and Sternum are coexistent in the same somatome, the 

 latter is on the inside of the former, and, as it develops, its perichondrium will be found to run 

 insensibly into the fibrous layer which lines the thorax, and also, most intimately, into the 

 pericardium. 



Example 4. Cryptobranchus japonicus, Bechstein. 



My figures of Cryptobranchus (Plate III, figs. 2 and 3) are taken from Professor Hyrtl's 

 work (plate v, figs. 1 and 3) ; they are of the natural ske. By comparing figs. 2 and 4 it will 

 be seen how much the corresponding structures are alike in Cryptobranchus and Menopoma ; 

 the supra-scapula (s. sc.) is not so broad relatively in the former as in the latter; but the prae- 

 coracoid (p. cr.) of Cryptobranchus is much the broadest, and is of an elegant elliptical shape ; the 

 cleft dividing it from the coracoid (cr.) is also more developed than in Menopoma, as is seen by 

 the position of the nerve-passage. The epicoracoid region (e. cr.) is also less produced anteriorly. 



