ANATOMY OF VERTEBRATES. 165 



is composed of three segments : the first, of two, rarely of three, 

 bones immediately articulated with the coracoid ; the next, of a 

 series of from two to six smaller bones ; which, lastly, support a 

 series of spines or jointed rays. These rays serially repeat the 

 branchiostegal rays in the hyoidean appendage, and the opercular 

 rays in the tympanic appendage. The vegetative repetition of 

 digits and joints, and the vegetative sameness of form in those 

 multiplied peripheral parts of the fins of Fishes, accord with the 

 characters of all other organs on their first introduction into the 

 animal series. The single row of fewer ossicles, figs. 34 and 

 81, 56, supporting the rays, 57, obviously represents the double 

 carpal series in Mammals ; and the bones of the brachium and 

 antibrachium seem in like manner to be reduced to a single series, 

 54, 55. In the ventral fin, fig. 34, v, no segment is developed 

 between the arch, 63, and the digital rays, 70 : it is in this respect 

 like the branchiostegal fin, 40, 44. 



The pectoral fin is directed backward, and being applied, 

 prone, to the lateral surface of the trunk, the ray or digit answer- 

 ing to the thumb is toward the ventral surface. The lowest of 



o 



the bones supporting the carpus should, therefore, be regarded as 

 the radius (figs. 34 and 81, 54), holding the position which that 

 bone unquestionably does in the similarly disposed pectoral fin of 

 the Plesiosaur, fig. 45, 54, and Cetacea. The upper bone, which 

 commonly affords support to a smaller proportion of the carpal 

 row, may be compared to the ulna (ib. 55). 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 dismember- 

 ment of it. In the Salmonida, it is more distinctly developed; 

 it is articulated in the Bull-trout (S. eriox} 1 to the middle of the 

 back part of the coracoid by a transversely elongated extremity ; 

 and is expanded at its distal end, where it articulates by cartilage 

 with the radius and ulna. 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 emargi- 

 nate anteriorly, 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. 



In the Bull-head and Sea-scorpion (Cottus), the radius and 

 ulna are widely separated, and two of the large square carpal 



1 XLIV. p. 18, No. 46. 



