53 
The axonost lettered 1 + 2 in figure 17 is also asym- 
metrical, its head inclining to the eyeless side. As this 
bone supports two fin rays (unlike any other in the body, 
except the huge axonost 1 of the anal fin), it was carefully 
examined in a very large plaice, and was there seen to 
present indications of three pieces, two of which possibly 
correspond to what would represent the first and second 
axonosts locked together, whilst the third is the partly 
cartilaginous proximal shaft wedged in between them and 
connecting them with the skull. If this interpretation of 
the first apparent axonost be correct, the first baseost 
(Bs. 1) will be situated between two axonosts as it should 
be, and not present an anomaly only found elsewhere in 
the skeleton of the plaice at the anterior extremity of the 
anal fin. Posteriorly near the head of axonost 1 + 2 is a 
recess into which fits baseost 1 for the second fin ray. 
Below this recess is a prominent projection which gives 
articulation to baseost 2 for the third fin ray. The second 
fin ray is asymmetrical, the ocular half being the longer. 
The third axonost and fin ray are practically sym- 
metrical. The head of this axonost forms a cone, the 
second baseost articulating in front and the third behind. 
Below the head the axonost bears leafy projections in 
front and behind. 
In the fourth axonost the leafy projections above are 
exaggerated and the shaft is reduced to a median ridge on 
each side of the axonost. This form of the axonost, 2.e., 
with a median spine on each side and thin lamin in front 
and behind, represents the typical structure of an axonost, 
and is admirably adapted for the muscles of the fin ray 
inserted into it. As described by Cunningham (pp. 47-48) 
in the Sole, each fin ray has six muscles, of which there 
is one on each side (the “right and left abductors’) for 
deflecting the fin ray to the right and left of the median 
