52 SHOULDER-GIRDLE AND BREAST-BONE. 



The post-temporal is forked, and the supra-clavicle is a sub-triangular plate ; the clavicle is 

 of an enormous she, and is bent backwards much more than in the Dory (Plate I, fig. 14, cl.). 

 There is a large ovato-oblong upper post-clavicle, and an extremely long lower post-clavicle ; so 

 that this Fish comes very near the spiny Globe-fishes in this respect (see Woodcut, fig. 4 C, 

 u. p. cl., 1. p. cl.). There is a very large, lanceolate membranous interspace between the concave 

 posterior outline of the clavicle and the concave anterior outline of the coracoid. The scapula 

 is semicircular, and has a rounded " notch " in front instead of the usual fenestra. The 

 synchondrosis between the scapula and prse-coracoid is very narrow, and almost horizontal ; and in 

 the latter bone the distinction between the prse-coracoid and the coracoid is but slightly evident, 

 for the inter-clavicular wings are of great extent, and the original cartilagious model has left but 

 little mark in this expanded bone. The coracoid reaches to the basal line below ; and it 

 seems very probably to have had originally some assistance from an " inter-clavicular " ossicle ; 

 otherwise the periosteal layers of the ectosteal sheath of the coracoid have indeed run riot. 

 The osseous substance of the true Shoulder-girdle is dense, but coarse ; that of the splint system 

 is extremely splintery, but these bones are stronger than those of the Balistidae, just as these are 

 stronger than those of Diodon and Ostracion. 



If there are any Genera lying in a direct line between these most aberrant Scomberoids 

 the Dory and Opah and the Plectognathi, a knowledge of their osseous structure would be 

 extremely interesting : perhaps some Semi-plectognatU may turn up. 



Fam. " PERCID/E." 

 Example. Muttus barbatus, Linn. 



The Shoulder-girdle of the Red Mullet differs in one important point from ordinary typical 

 Acanthopterous Fishes, namely, in the presence of an additional fenestra to the scapula. The 

 Woodcut (fig. 6 E) shows the left coraco- scapular plate from the outside, and magnified two 

 diameters. The letters a. f. indicate the anterior fenestra; p. f., the posterior; p. sc., the prae- 

 scapula ; m. sc., the meso-scaptila ; and sc., the scapula proper, or post-scapula. The glenoid 

 region (gl.) is principally scapular ; the synchondrosis is moderate ; the prse-coracoid (p. cr.) very 

 broad ; the moderately developed inter-clavicular wings of the coracoid (cr.) have an average size. 

 I have not hitherto seen any other instance of the additional fenestra of this scapula in Osseous 

 Fishes, but I have already described it in the Skate (Plate I, fig. 2) ; here, however, the anterior 

 fenestra is coraco-scapular ; that this makes no real difference will be seen from my next instance, 

 namely, the Cod, in which the single fenestra belongs to both regions. 



When we come to the Lacertilia, this triple condition of the scapula will be seen again ; and 

 it is very clearly indicated in certain Mammalia. 



The Order Anacanthini is not very far removed from the Acanthopteri typici in the 

 structure of their Shoulder-bones ; but there are differences worth noticing. It was in observing 

 the structure of the common Cod-fish that I first saw the relation of the true Shoulder- girdle to 

 its splints, and also that the coracoid of this and of typical Fishes generally is essentially a double 

 or forked ray a view the truth of which can be easily demonstrated by a reference to the state 

 of these parts in the Carp and its congeners. 



