tECULIAlailES 01* PLAICE FHOM Dlt'fERENT I'ISIIING GliOUNUS. 325 



specimens from the Brown Eidges, because the difference is not greater 

 than that which I have shown to exist in the length of the smallest 

 mature in the two cases. The largest specimen from the Norfolk coast 

 has the fourth degree of spinulation. Taking all these facts into con- 

 sideration, I conclude that on the whole the spinulation is slightly but 

 distinctly greater in the plaice from the Norfolk coast than in those 

 from the Brown Bidges. 



In the females also there is a slightly more frequent spinulation 

 among the specimens from the Norfolk coast than in those from the 

 Brown Badges. It is rare to find any trace of the condition in the 

 females, but it is by no means exclusively confined to the oldest or 

 largest specimens. One of the three spiuulated females from the 

 Norfolk coast was only 27"0 cm. long, and apparently immature. 



The much greater development of spinulation in the plaice from 

 beyond the Dogger Bank is very evident from the figures. But we 

 must consider how far this may be due to the greater age of the 

 specimens, since the locality where they were captured is in greater 

 depth of water and much farther from the coast than the district off 

 the Norfolk coast, or even the Brown Ridges. Now in the males 

 of the deep-water sample there are eight specimens over 40 cm. in 

 length, the largest being 47*3 cm. long ; of these, in the smallest 

 specimen, the degree of spinulation is 2, in the largest 5, and in the 

 other six 4. Of the males from the Norfolk coast, six are over 

 40 cm. in length, and the largest is 48-9 cm. long ; of these three have 

 degree 2, one degree 3, and two only have degree 4. We have no 

 reason to suppose that the northern specimens are older, although not 

 larger; the presumption is the contrary. Therefore we have suflicient 

 proof that the plaice from the more northern locality are considerably 

 more spinulated at the same age than the Norfolk coast specimens, and 

 a fortiori than those of the Brown Bidges. There is evidence that the 

 development of spinulation increases with age; but enough evidence has 

 been here produced to show that the difference between my samples 

 from different localities is not due to differences of age. 



It may be pointed out as worthy of note that in the two females 

 in which spinulation occurs among the specimens from beyond the 

 Dogger Bank, it is present on the cheek, and almost entirely absent 

 from the fins. 



The males from Plymouth appear to be rather more spinulated than 

 those from the Brown Bidges ; but it may be mentioned that in the 

 specimen which is recorded as having degree 4, the spinulation of the 

 interspinous regions was only just perceptible. 



RccaintuUdion. Tiie investigation shows that although the number 

 of individuals examined is not so large as it ahould be, yet there are 



