12 SATi:i;l)AY I.IXTIKES. 



tween it and the (juasi-peduiK-ulatcd tin. Y\'hat are these, and 

 how are they comparable with the anterior members and 

 appendages of a wliale? [ am eom])elled to admit at once 

 that we cannot compare them directly, and if we attempted 

 to do so, we would almost inevitably fall into gross error; 

 indeed, the old anatomists who made the attemp^t did so. 

 Men, illustrious in science, like Cuvier, Agassiz, and Owen, 

 considered the i\mv longish bones we have noticed as carpals, 

 and the two externally fiattish bones which support them 

 as the radius and ulna. To ascertain their true nature, we 

 have to avail ourselves of extraneous evidence. I am, 

 therefore, compelled, in justice to you as well as to myself, 

 to make a .slight digression. 



Let us now examine for a moment the skeleton of polyp- 

 terus, to which we have before referred. 



The pectoral fin oi polypterus has rays which are essentially 

 similar to those of the salmon, and at the base of those 

 rays are a number of nearly parallel longish bones which 

 resemble the four at the base of the rays in. the salmon. In 

 polypterus we also find a shoulder girdle which is not unlike 

 that of the trout. But now please direct your attention to 

 the inner side of the principal bone of that girdle and 

 instead of three bones, as in the salmon, you will find there 

 is a single large piece ; that piece has a peculiar kind of 

 projection which is divided b}^ a partial constriction from 

 the body of the bone and reminds one of a ball. Ar- 

 ticulating with this are two long diverging processes. 

 Between these processes is to be especially observed a flat 

 cartilaginous mass which also intervenes between them and 

 the parallel longish bones. 



To understand the structure thus revealed, examine now 

 the pectoral fin and shoulder girdle of the common gar-pike 

 of the Potomac river — the lepidosteus osseus of naturalists. 

 The fin has rays like those of the polypterus and salmon; it 

 has also the longish bones at the base. The shoulder girdle 

 is developed as in them, but with special characters of its 

 own. But the inner piece attached to the chief bone of the 

 girdle is especially noteworthy. As in the polypterus, it is 



