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Proceedings of the Royal Society of Edinburgh. [Sess. 
conjoined carpalia 4 + 5, or indeed in the carpal extremity of the ulna itself. 
It should be noted that in one of the adults the carpal end of the ulna 
was fused with the conjoined carpalia 4 + 5, and the relatively large bone 
produced had a complex composition (fig. 4). 
In all the specimens a bone was intercalated between the radiale and 
carpale 1 on the one side, and the intermedium and carpale 2 on the other. 
It articulated with these bones, though in two adult hands it had fused 
with the radiale element of the conjoined radiale-carpale bone (fig. 5). From 
its position and relation it was evidently an os centrale (figures). From its 
occurrence in each carpus the centrale is to be regarded as a constant bone in 
the manus of Platanista. An ossified pisiform was not present in any of the 
specimens. In the carpus of the younger animals unossified cartilage was 
present at the ulnar margin, but a pisiform cartilaginous element did not 
seem to be differentiated. 
The largest number of bones present in any of my specimens was seven, 
viz. intermedium, radiale, carpalia 1, 2, 3, carpalia 4 + 5 fused into one bone 
and os centrale. Ktikenthal also saw in the Leiden Museum a carpus with 
seven bones and in the Museum of the London College of Surgeons one with 
eight bones, due to the presence of two centralia. Six, however, is the pre- 
vailing number in the majority of my specimens. Reduction in number was 
due either to fusion between bones of the proximal and distal rows, as 
when radiale was fused with carpale 1, to constitute the radiale-carpal bone, a 
condition which was frequent ; to fusion between bones in the same row, 
carpale 4 with carpale 5, constant ; fusion between os centrale and radiale, of 
which I had two specimens (fig. 5) ; fusion between carpalia 4 + 5 and ulna 
(fig. 4). The absence of ulnare and pisiform was probably due to their non- 
development even in the cartilaginous stage of the carpus. 
I differ from Anderson in regarding the bone which he called radiale as 
an os centrale, and in this respect I concur with Ktikenthal. Anderson 
described only three bones in the carpus of one of his specimens, which 
reduction, to employ the nomenclature used in this memoir, was due to 
fusion of radiale-carpale with os centrale, intermedium with carpale 3, 
ulna with conjoined carpalia 4 + 5; carpale 2 therefore was the only carpal 
element which had not fused.* 
As a rule the carpal type in Platanista from the radial margin to the 
intermedium agreed with Hyperoodon, except in the tendency for the 
radiale to fuse with carpale 1 and the more constant presence of an os 
* The names given by Anderson to the carpal bones differed from those used in the text. 
The radiale-carpale is his trapezium, the os centrale his radiale, carpale 2 the trapezoid, 
carpale 3 the magnum, carpalia 4 + 5 the cuneiform. 
