ANATOMY OF VERTEBRATES. 1G5 



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

 bones immediately articulated with the coracold ; 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 

 branehiostegal 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 

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

 characters of all other oro-ans on their first introduction into the 

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

 81, 5(;, snpporting the rays, 57, obviously represents the double 

 car})al series in JNIammals ; and the bones of the brachium and 

 antiln-achium 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, 6.3, and the digital rays, 70 : it is in this resi)ect 

 like the branehiostegal fin, 40, 44. 



The pectoral fin is directed backward, and being api)lied, 

 prone, to the lateral snrlace of the trnnk, the ray or digit answer- 

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

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

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

 lionc unquestionably does in the similarly disposed pectoral fin of 

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

 commonly aftbrds support to a smaller proportion of the carj^al 

 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 immatiu-c 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 dismemlDcr- 

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

 it is articulated in the Bull-trout (S. erioxY to the middle of the 

 back part of the coracold I)y 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 himierus : in 

 these the ulna is a short and broad plate of bone, deejily emargi- 

 natc anteriorly, attached by suture to the coracoid, and by the 

 onposite 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 



' XLiy. p. 18, No. 4 6. 



