40 
Branchial Arch I¥.—The cerato-branchial is less 
strong on this side, but on the other hand the epi- 
branchial is larger. The cerato-branchial does not articu- 
late with the fourth basi-branchial but with the corre- 
sponding segment of the ocular side. 
The Superior and Inferior Pharyngeals.—The asym- 
metry in the number of the teeth is so strongly marked in 
the mouth, where the ocular side is practically devoid of 
them, that it is interesting to enquire whether its effect 
has been felt as far back as the pharyngeal bones. In 
the inferior pharyngeal the two sides are practically the 
‘same, except that in the specimen described the ocular 
bone bore two less teeth. The left superior pharyngeal, 
however, was appreciably the larger, and although it only 
possessed an advantage of one in the number of teeth, the 
teeth themselves were larger and capable of doing more 
work. ‘This is doubtless due to the fact that in an animal 
lying on its left side, its food, even in the pharynx, 
naturally gravitates to the latter side. 
7.—VERTEBRAL CoLuMN.* 
(Figs,10,.11, 12;13,°I4) 17,918; 19). 
The vertebral column of the Plaice may be divided 
into a trunk and tail region only, distinguished in the 
former by the presence of ribs and in the latter by the 
haemal canal. Although the number of vertebre in the 
column is subject to variation, it usually happens that the 
first caudal vertebra is the fourteenth. 
Each vertebra is markedly amphicoelous, the anterior 
and posterior faces being considerably scooped out in the 
*The structure and development of the vertebral column of 
Teleostean fishes has recently been studied by S. Ussow (Bull. Soc. Imp. 
Nat., Moscou, 1900, p. 175). Also previously in Amia and other fishes, by 
O. P. Hay (Field Columbian Museum, Zool. Ser., vol. i., No. 1, 1895). 
