296 Proceedings of the Royal Physical Society. 



some others which, judging from their distribution, may also 

 occur within the Forth area, though hitherto they have 

 escaped notice. I have already mentioned that Scottia 

 Browniana has been observed in a lacustrine deposit at 

 Elie, Fifeshire, and as it appears to be very local in its 

 distribution, it may yet be found living somewhere within 

 the district. Gypridopsis Newtoni is another that may be 

 expected to occur in some of the inland waters, and there are 

 also a few marine forms that are likely to be met with. 



About 170 species have, I think, been recorded from Scot- 

 land (including the Orkney and Shetland Islands), and if 

 those which have hitherto been only observed in the neigh- 

 bourhood of Shetland be excepted, it will be found that fully 

 84 per cent, of the Scottish species are represented within 

 the Forth area. 



Order COPEPODA. 



The Copepoda comprise a much larger number of species 

 than any of the other Crustacean orders. The species 

 enumerated here amount to 306, and include both free- 

 swimming and parasitic forms. 



Various methods have been adopted for the scientific 

 arrangement of these organisms. In that used by Professor 

 G. 0. Sars in his great work on the Crustacea of Norway, now 

 in course of publication, and which for the sake of uniformity 

 I propose to follow generally, the Copepoda are separated 

 into seven divisions, viz. : — 1st, the Calanoida, most of which 

 are free-living and pelagic; 2nd, the Harpacticoida, which 

 for the most part are free-living but demersal ; 3rd, the 

 Cyclopoida, some of which are free-living fresh- water species, 

 while others are " semi-parasites," and live as commensals or 

 messmates with various other organisms ; 4th, the Noto- 

 delphyoida, which, for the most part, are "semi-parasites," 

 associated with various Ascidians ; 5th, the Monstrilloida, 

 a small but curious group, which appear to live a partly 

 parasitic and partly free life; 6th, the Caligoida, chiefly 

 parasitic on fishes, but some of which possess a certain 

 freedom of movement; and 7th, the Lerna3oida, fish para- 



