NORTHERN SPECIES OF ORCA. 



173 



humerus occupied 5" 2'", the fore-arm 5", the carpus 2", the metacarpus also 2", the longest finger 

 6" 10'", and the skin on the point 1" 6'". The greatest breadth is at the root of the thumb, namely, 

 at a distance of 10" 4"', from the extreme point of the manus, and 12" 2"' from the most ante- 

 rior point of the humerus. The greatest breadth of the humerus was at its posterior extremity, 

 where it measured 4" 4"'. The bones of the fore-arm had a breadth of 5" 8"' at their anterior 

 extremities (the radius 3" 2"', the ulna 2" 4"'), in the middle a breadth of 4" 10"' (the 

 former 3", the latter 1" 8"'), and posteriorly a breadth of 7" 6"' (the radius 2", the 

 ulna 5" 4"'). The carpus consisted of five bones, four of which (No. 1, 2, 3, 4, in the 

 woodcut) formed an anterior row ; the radius was 

 in contact with No. 1 and 2, the ulna with 2, 3 

 and 4. Of the metacarpal bones, that of the 

 thumb was contiguous with No. 1 ; that of the 

 second finger with Nos. 1 and 5 ; that of the 

 third with Nos. 5 and 3 ; that of the fourth with 

 Nos. 3 and 4 ; and that of the fifth with No. 4 

 alone. The thumb is placed close up to the 

 radial margin of the manus, has only one phalanx 

 (besides the metacarpal bone) and reaches only 

 to the middle of the first phalanx of the second 

 finger. This is considerably longer than any of 

 the others, and composed of six phalanges; be- 

 sides, it is very much curved, being parallel with 

 the radial edge. The third finger has only four 

 phalanges, the fourth three, both pointing towards 

 the ulnar edge of the manus ; but the fifth 

 finger, having only two phalanges, and placed on 

 a level with the first row of bones of the carpus, 

 has a perfectly transverse direction, meeting the 

 projecting corner on the ulnar edge of the 

 ' manus. 



That the pectoral fins of the killers diff'er 

 from those of all other toothed-whales by being 

 very large, generally speaking, and besides by 

 being almost equally long and broad (the propor- 

 tion of the length to the breadth is as 6 : 5), 

 may to a very great extent be ascribed to this 

 transverse position of the fifth finger and the 

 strong curvature of the second and longest; 



but this peculiarity is also produced by the form of the phalanges, as they are all very broad in 

 proportion to their length, by which means any single phalanx may in general easily be distin- 

 guished from the phalanges of ail other toothed-whales. Their superior breadth is, however, 

 principally to be found in their extremities, so that the hour-glass form, so common in these bones 

 of the Cetaceans, is here very conspicuous. 



We know that in the Cetaceans all the bones of the manus are in general only incompletely 



