718 Proceedings of the Royal Society of Edinburgh. [Sess. 
fusion of C 5 with M v , or from an early atrophy and disappearance of the 
cartilaginous C 5 . 
The question whether C x is present or absent in some species of 
cetacea has been a matter of discussion. There can be no doubt of its 
presence in Mesoplodon, Hyperoodon, Beluga and Grampus. In Lageno- 
rynchus and Phocoena it was absent, and M r articulated directly with the 
radiale, with which C x might have fused ; though, as Leboucq has shown 
in Monodon monoceros, the fusion of C x with Mj does at times undoubtedly 
take place. In Delphinus, again, the question has arisen whether the bone 
immediately distal to the radiale is to be regarded as M x or C 1 . If the 
former, then the pollex would possess two phalanges, and its metacarpal 
would articulate directly with the radiale. If the latter, C x would be 
interposed between the radiale and M l5 and the carpus would possess 
three disto-carpals. I have adopted the latter interpretation and applied 
it also to the carpus of Globicephalus. 
As regards the os centrale, Mesoplodon and Globicephalus furnished 
examples of the presence of an os centrale as an independent bone ; in the 
right manus of the St Andrews Mesoplodon a second centrale had been 
developed, and in that from Dalgety Bay an os centrale had fused with the 
radiale. In Monodon the centrale was fused with the intermedium. In 
the Struthers collection of cetacea, already referred to, is the dissected 
hand of an adult cetacean which, though not marked, is I believe that of 
Hyperoodon A The carpus consisted of ten bones and cartilages, three in 
the proximal row; live separate disto-carpalia, of which C x and C 4 were 
well ossified, C 2 and C 3 partially so, whilst C 5 and the pisiform were 
unossified. An almond-shaped unossiiied os centrale, 21 mm. in transverse 
and 14 mm. in vertical diameter, was intercalated on the palmar surface 
between the radiale, intermedium, carpalia l and 2 . In the presence of 
an os centrale this specimen corresponded with specimens of Hyperoodon, 
two well grown and a foetus, as described by Ktikenthal. In Beluga 
an unossified piece of cartilage probably represented the centrale. 
Ktikenthal came to the conclusion from his observations on embryos that 
centralia are not unfrequently present in the early stages, but that they 
commence to disappear when other elements in the carpus lose their 
* This limb probably belonged to the Hyperoodon which Professor Struthers obtained 
in 1871, and the finger muscles of which he described in the Journal of Anat. and Phys ., 
vol. vi. p. 115. At the Aberdeen meeting of the British Association, 1885, he exhibited 
the carpus of Hyperoodon along with those of other cetacea, but no description was 
published. Report , p. 1056. The radio-ulnar epiphyses were fused with their shafts. The 
radiale, intermedium, and ulnare were respectively 43, 58 and 45 mm. wide ; the disto- 
carpalia 1 to 5 were 39, 33, 35, 27, 30 mm. respectively. 
