120 LECTURE V. 



fishes, accord with the characters of all other organs on their first 

 introduction into the animal series. The single I'ow of fewer ossi- 

 cles supporting the rays, obviously represents the double carpal series 

 in Mammals ; and the bones of the brachium and anti-brachium seem 

 in like manner to be reduced to a single series, unless the humeral 

 segment be confluent with the arch. In the ventral fin no segment 

 is developed between the arch and the digital rays : it is in this 

 respect like the branchiostegal fin. 



The pectoral fin is directed backwards, and being applied, prone, 

 to the lateral surface of the trunk, the ray or digit answering to the 

 thumb is towards the ventral surface. The lowest of the bones sup- 

 porting the carpus should, therefore, be regarded as the radius 

 {figs. 19. and 30. 55), holding the position which that bone un- 

 questionably does in the similai-ly disposed pectoral fin of the 

 Whales and Enaliosaurs. The upper bone, which commonly aifords 

 support to a smaller proportion of the carpal row, may be com- 

 pared to the ulna (ib. 54). As a third small bone is articulated to 

 the coracoid, in some Osseous Fishes, at least in their immature state, 

 the name of humerus may be confined to that bone : but in these it 

 is generally above and on the inner side of the ulna, and seems to be 

 rather a dismemberment of it. In the young Tench, however, the 

 humerus is a small ossicle, firmly attached to the inner surface of the 

 coracoid, and articulated at the other end to both the ulna and the 

 radius, but not reaching to the carpus. The ulna is beneath it, and 

 of an annular form ; the radius is much larger, and of a triangular form, 

 articulated by its smallest side with the humerus and ulna, by its an- 

 terior and outer border with the coracoid, and by its upper and hinder 

 border with the carpus. In the Cod, Haddock, and most other fishes, 

 there is no separate representative of the humerus : in these the 

 ulna is a short and broad plate of bone, deeply emai'ginate an- 

 teriorly, attached by suture to the coracoid, and by the opposite 

 expanded end to the radius, and to one or two of the carpal ossicles, 

 and directly to the upper or ulnar ray of the fin. 



Tlie radius (^ib. 55) is a crescentic or sub-triangular plate with 

 an upper emargination completing an interosseous foramen with that 

 of the ulna ; articulated by a small part of its upper and anterior 

 angle and by its produced lower and anterior angle with the coracoid, 

 so as to permit a slight movement, and having its uj^per and hinder 

 border equally divided between the ulna and the carpus. In the 

 Bull-head and Sea-scorpion (Cottus), the radius and ulna are widely 

 separated, and two of the large square carpal plates in their inter- 

 space articulate directly with the coracoid. A similar arrangement 

 obtains in the Gurnards and the Wolf-fish ; but the carpals in the 



