yd 
od 
baseost and axonost is a very slight non-ligamentous one, 
and hence the fin ray and baseost are only held down in 
the soft cartilage cup at the head of the axonost by the 
elevator and depressor and right and left abductor muscles 
(Z’.R. e) of the fin ray. The result is that the fin ray and 
baseost are capable of being moved on the axonost in any 
direction. The axonosts are held in position by two liga- 
ments: (a) by a longitudinal vertical ligament which 
keeps the axonosts at their correct distances from each 
other and separates the right and left series of the fin-ray 
muscles; (6) by transverse ligaments (Az. a) which keep 
the axonost from moving from side to side. The head of 
the axonost contains a triangular plug of typical hyaline 
cartilage (Aw. b) as before mentioned. The whole appa- 
ratus is somewhat asymmetrical as shown in the figure. 
The attached table, based on the examination of a 
52cm. plaice, has been drawn up to show the number, 
position, and precise relations of the ribs, neural and 
haemal spines, and skeleton of the dorsal and anal fins. 
The specimen had 42 vertebre (cp. figs. 17, 18 and 19). 
The division into regions is somewhat arbitrary, since for 
example the boundary between the cranial and occipital 
regions is along the axis of fin ray 9 and baseost 8, @.e., 
between axonosts 8 and 9. In the anal fin the axonosts 1 
to 7 are situated morphologically between vertebre 15 and 
14 (cp. fig. 18), and hence at this region (as 
indicated by the line) the correspondence between the two 
regions of the table has no morphological value. Behind 
this ambiguous region (.e., behind and _ including 
vertebre 14) it will be noticed that although there is a 
very wide disagreement in the disposition of the fin skele- 
ton above and below the vertebral column, yet the 
numbers of the fin rays are practically the same, z.e., 45 in 
