54 SHOULDER-GIRDLE AND BREAST-BONE. 



skeleton is concerned, the Salmonoids, Cyprinoids, and Clupeoids, go together to form 

 another group ; at any rate, they most clearly foreshadow the Amphibia in the structure of 

 their Shoulder-girdle. The plan of this Memoir, however, embracing, as it does, the Shoulder- 

 bones of all the Vertebrata, does not allow me to linger amongst the Fishes, but only to 

 catch up the chiefest modifications, so as to throw light upon these structures in the whole 

 " Sub-kingdom." l 



Fam. 



Example. Anr/uilla acutirostris , Yarrel. 



My dissections of the Sharp-nosed Eel were made from very young specimens ; the one 

 whose Shoulder-plates are figured (Plate II, fig. 9) as magnified twenty diameters, measured 

 three inches in length. There is no post-temporal; the post-clavicle also is absent; but the 

 supra-clavicle (s. cl.) is a strong rod, slightly bent backwards, blunt above, pointed and flat 

 below ; both this bone and the clavicle are very solid, rounded bones for a Fish. The lower 

 splint-bone (cl.) is like the one above it, but is twice as long and twice as thick ; it is reduced to a 

 rounded point above, where it is somewhat flattened, and it is pointed below ; above the point there 

 is a scooped space on the outside. Altogether, the clavicle of the Eel comes very near to that of 

 the Blindworm (Anguis] ; it is very loosely connected with the true Shoulder-girdle moiety. 



The inner element of the Eel's Shoulder is a flat four-sided plate with all the angles except the 

 postero-inferior, produced into a more or less rounded process. It is of moderate thickness, but 

 very flat on both sides ; the bony scapula and coracoid have both appeared as semicircular 

 ectosteal plates. The former (sc.) is placed between the ascending, long, anterior process of 

 the cartilage and the shorter posterior lobe ; it is like a saddle, and the unchanged cartilage 

 simulates the neck and rump of the Horse. Antero-inferiorly there is an oval " fenestra " (sc. f.), 

 with its narrow end backwards, and its broad end reaching the cartilage in front ; the back of the 

 saddle-shaped bone is sinuous. The coracoid (cr.) is much like the scapula, but broader, and it 

 has no fenestra ; there is a large " clavicular," a " glenoid," and a " synchondrosial " tract of soft 

 cartilage. The glenoid region is at first concave, and then convex in outline ; it is in relation 

 with eight drumstick-shaped brachials (b. 1 8), which are small, and feebly ossified, being soft 

 at their enlarged ends. 



My first Abdominal Physostomous Fish belongs to a group which looks towards the 

 Lepidosteus. 



Jam. 

 Example. Esox Indus, Linn. 



As the splint-bones of this Fish are, on the whole, typical, I shall confine myself to the 

 true Shoulder-girdle. The specimen dissected and drawn (Plate II, figs. 10, 11) measured six 

 inches in length, and the figures are magnified twelve diameters. Fig. 10 shows the left moiety 



1 The position of the Gasterostei with their abdominal " ventral " fins, is very doubtful. The 

 ligament which binds the anterior extremity of their swim-bladder to the upper part of the alimentary 

 canal is always perforated in an early stage. 



