62 SHOULDER-GIRDLE AND BREAST-BONE. 



as magnified two diameters, from Professor Hyrtl's dry preparation of an adult female from 

 Carolina ; but as the cartilages were somewhat spoiled by drying, 1 have finished this figure from 

 the woodcut made from one of Sir Charles Bell's beautiful sketches (Fourth Bridgewater Treatise, 

 page 68). The supra-scapula (s. sc.) is rather small and elegantly fan-shaped ; the scapula (sc.) 

 is a phalangoid shaft of bone reaching up well above, but, although broad, deficient below. The 

 prse-coracoid (p. cr.) is knife-shaped, and the main coracoid more pointed at the ends than is usual. 

 The nerve-passage is well shown, and the glenoid region is unossified, neither reached by the 

 scapula above nor by the new bone, the coracoid, behind and below. 



The coracoid shaft-bone (cr.) only covers half its own region, and is semi-oval, and thick at 

 its concave, free, upper margin ; its lower edge defines the epicoracoid (e. cr.) region behind. No 

 Sternum is to be seen in Hyrtl's preparation, although I should suppose that it might be found 

 in the fresh specimen. 



Example 2. Amphiuma didactylum, Cuv. 



In this Amphibian I have been enabled to get a fuller conception of the Shoulder-girdle by 

 referring to Hyrtl's work (plate v, fig. 4) as well as to his dry preparation of the parts. My figure 

 (Plate IV, fig. 4) represents the inside of the right moiety, magnified four diameters. There is 

 no Sternum to be found in the preparation, and I question very much whether it could be seen in 

 the fresh state. This I infer on account of the very small relative size of the parts, and their 

 persistent separation from each other on the sides of the thorax. The supra-scapula (s. sc.) is 

 small and sub-triangular ; the scapula (sc.), a somewhat curved and rather flattened ray, ossified 

 as a shaft ; whilst the rest of the structure is an irregularly bilobed convexo-concave plate. The 

 prse-coracoid (p. cr.) is only slightly cloven from the other part by a triangular notch ; there is a 

 relatively large, squarish, bony coracoid (cr.) entirely insulated by cartilage, even along the glenoid 

 margin, and towards the base of the scapula : all the epicoracoid (e. cr.) continues soft. 



c. With three Ossifications in each moiety of the Shoulder-girdle. 

 Example 1 . Phtenerobranchus mexicanus, Wagler. 



The right moiety of the Shoulder- girdle of this Mexican Amphibian, is drawn from the 

 skeleton of an adult female in the Hyrtl Collection (Hunterian Museum) ; it is magnified three 

 diameters (Plate III, fig. 6). Here, again, I miss the Sternum, which must have existed in the 

 fresh state ; but I am glad of what I have found, namely an additional instance, besides that of 

 the Newts and Salamanders, in which the three main regions of the Shoulder-girdle are 

 to some extent ossified. In mere outline, this structure is like that of the Axolotl, but 

 the prse-coracoid (p. cr.) is rather less, and diverges more ; the scapular shaft (sc.) has 

 ascended higher and descended lower, and has met and to some degree coalesced with a 

 small, square, proximal prse-coracoid (p. cr.), and with a much larger, and very irregular 

 coracoid (cr.) The large nerve-passage is seen to be in the suture between the prge-coracoid 

 and the coracoid. 



