K 
54 
plane and which are not connected with the shafts of the 
axonosts, whilst the other four (the “ elevators and depres- 
sors”) are arranged 2 on each side, the anterior right and 
left pair arising from the anterior surface of the fin ray 
and being inserted into the lamina on the shaft of the 
axonost in front of the median spine, the posterior pair 
arising from the posterior surface of the ray and being 
inserted into the posterior lamina. The latter muscles 
elevate and depress the fin ray in the median plane. 
If the dorsal surface of the cranium cf a plaice be 
examined, there will be noticed in the pseudo-mesial plane 
a longitudinal trench-like depression which passes back- 
wards in a slight sigmoid curve from left to right on the 
left frontal and supraoccipital. ‘This depression (see fig. 
1) is connected with the extension forwards of the dorsal 
fin over the roof of the cranium. Into it fit usually 
axonosts 6, 7, 8, whilst the axonosts in front of these, 
though too short to actually reach the cranium, are con- 
nected with the depression by means of ligaments. 
Behind the attachment of the eighth axonost, the ceciput 
suddenly shelves down, and in this depression, 2.e., 
bounded in front by the reduced occipital spine and 
behind by the first neural spine, are situated the two suc- 
ceeding axonosts (9 and 10). Behind the 10th the 
axonosts become related to the neural spines as usual. 
The posterior extremity of the dorsal fin is only note- 
worthy in two respects: (a) in the presence of 4 axonosts 
between neural spines 36-37, the largest number found 
between any two succeeding neural or haemal spines, 
excepting the anterior extremity of the anal fin; (0) the 
last fin ray (71) articulates directly with the axonost (70) 
without the intervention of a baseost. The last four 
vertebrae have no connection either with the dorsal or anal 
fins. In the specimen on which the above description was 
