PEOrESSOE OWEN ON INDIAN CETACEA. 43 



the twentieth (or forty-first from the skull), leavmg ten, perhaps eleven, termmal 

 vertebrse represented by depressed centrums, gradually dimmishuig to the last. The 

 seven cervicals are anchylosed : the diapophyses distmguish the atlas and axis, the former 

 of which vertebra; does not retam, as in Phjsefer, its separate condition ; the fifth, sixth, 

 and seventh are lamelliform, from extreme anteroposterior compression. The dorsal spines 

 progressively, but very graduaUy, gam in height to the last; beyond which they agam, 

 and more rapidly, shorten to the base of the tail, disappearing in the fortieth vertebra 

 from the skull. The metapophysis begins to project above the prozygapophysis in the 

 fifth dorsal, and supersedes that process in the articulation of the neural arches in the 

 seventh or eighth dorsal. The four anterior pahs of ribs dkectly join the sternum, 

 which consists of three sternebers, each more or less completely divided at the middle 

 Ime mto two bones. The first rib is b]-oad, flat, and angularly bent, articulated by the 

 tubercle to the first dorsal diapophysis, and by a ligament representmg the head to the 

 centrum of the seventh cervical : its coimate sternal portion articulates with the antero- 

 extemal angle of the manubrium. The second and six following ribs have both head 

 and tubercle, the former abutting against the interspace of theh o\^ai and antecedent 

 centrums ; the tubercle of the rib is attached to the diapophysis of its own vertebra : 

 the second rib, less broad but one-fourth longer than the first, has a short, partly 

 ossified cartilage, which joins the interspace between the first and second sternebers. 

 The thhd, gammg length, losing breadth, and with more regular curvatm-e, is arti- 

 culated by its short hsemapophysis to the interspace between the second and third 

 sternebers . The fourth rib is j oined to the end of the third stemeber . After the seventh the 

 ribs lose their heads, become shorter, more slender, less curved- — gradually to the tenth, 

 which is 9 inches in length — suddenly in the fourteenth, which is a straight style 

 is hardly an inch long. There are two pairs of pelvic bone. The pectoral fins are 

 relatively short and rather obtuse. The scapula is a flat triangular plate, with a con- 

 vexly curved base, in extent equalling the fore-and-aft range of the five anterior dorsal 

 spines. An obtuse rising near the anterior costa, at its humeral half, developes near 

 the glenoid cavity a small coracoid directed forward. The acromion is much larger, and 

 is produced from a greater extent of the anterior costa in the form of a parallelo- 

 gram. The ulna developes scarcely any olecranon. There are five digits : the first and 

 fifth are the shortest, each with a metacarpal and two phalanges; the second and 

 third digits are the longest, with five and four phalanges respectively, besides the 

 metacarpal ; the fourth digit, intermediate in length between the third and fifth, has a 

 metacarpal and four phalanges. 



Conclusion. 

 The first remark that I am led to make on a review of the cetacean characters above- 

 defined in connexion with those previously recorded is, that they are all gradational, 

 and exemplify steps by which are gained the extreme modifications, especially in the 



skull and dentition. 



g2 



