194 
posterior wall of the body cavity. At this age, and for 
some considerable time afterwards, it is quite impossible 
to distinguish between male and female gonads without a 
microscopical examination. The growth of ovaries or 
testes is extremely slow during the first two years of life, 
that is up to 6-8 inches long. After this age the ovary 
can be readily distinguished from the testis. It is a 
paired conical shaped structure. The base just projects 
into the posterior part of the body cavity; the apex pro- 
jects backwards towards the tail, lying between the 
haemal spines and the muscles of the trunk. The oviducts 
are extremely difficult to dissect and do not open exter- 
nally. In the follewing year the organ rapidly develops. 
In male Plaice of the same size the testes are paired 
ridges of the posterior body wall projecting forwards into 
the body cavity, but having no extension backwards as in 
the case of the ovaries. 
The Female organs. —l'ig. 20 represents the condition 
of the ovary in a mature and nearly ripe Plaice. The 
specimen figured was captured in December. The ovary 
is seen to project far forward into the body cavity, dis- 
placing various organs from their normal positions. Part 
of the posterior extension of the organ is indicated in the 
figure ; it really extends backwards to near the root of the 
tail. Its posterior portion lies along the external surface 
of the haemal spines. and is only separated from these by 
loose areolar tissue. ‘The overlying muscles of the trunk 
are very thin, and occasionally the ovary appears to be 
covered only by integument and connective tissue. In 
this condition it can be felt externally as a hard pad lying 
on either side of the ventral portion of the body behind 
the anus. The ovary of the ocular side appears to be, 
sometimes at least, more strongly developed than that of 
the eyeless side. 
