— 264 — 



on the other hand, hâve a gréai nuraber, and thèse may be divi- 

 ded into thrèe groups. 



The first group comprises tlie Broads of theThurnë river — 

 Martham, Heigham Sounds, Hickling, and Horsey 

 — ail of which are characterised bv the high salinitv of their 

 vvaters. The fauna is peculiar in thaï il ineludes Neomysis 

 vulgaris, Gammarus Duebeni anàCordylophora lacustris. 

 The flora is remarkable for the great abundance of Chara- 

 ceae and of Potamogeton pectinatum. A number of species 

 of Crustacea fonnd commonly in other Broads arc absent from 

 tliis group. 



The second group is made up of the Broads of the Ani — 

 Ba rton and Sutton. Thèse two are sliallow, weedv Broads, 

 with a very rich fauna of littoral species but with no purely 

 pelagic species of Entomostraca. They hâve several })oints 

 in conimon with the first group. The Broads of botli groups 

 hâve a very rich végétation over nearly their whole area; species 

 of Characeae occuring in ail of them, but not in any abun- 

 dance in any other Broads on the Bure. In none of them are 

 tria 1 pelagic species of Entomostraca found except on very rare 

 occasions, and those species which are usually pelagic {Bosm i na) 

 and true bottoni forms (e. g., Ilyocryptus) are much less com- 

 nion in thèse Broads Iban in those of the third group. 



The Broads on the Bure itself— Ormesby, Rollesby, and 

 Filbv, South Walsham, Ranworth, Hoveton, Sal- 

 house, and Wroxham, — form a third group. South Wals- 

 ham and Ranworth stand somewhat apart from the rest in 

 that they coin» 1 to some extent within the reach of marine 

 influence, as shown bv the présence in them of Tachidius litto- 

 ralis. Ormesby. Rollesby, and Filbv also differ from the 

 rest in having no direct connection with the river. Ail agrée 

 in being, on the whole, deep, with little or no submerged 

 végétation except lien' and there near the shores. Their shores 

 are generally sharply dëfined. Their water is quite fresh, 

 and they hâve a rich Plankton, consisting niainlyof Diatoms, 

 but with abundance of Daphnia cucullata. 



Noue of the Broads of the Thurne and Ani corne within the 

 accepted définition of a true •• Lake », since their deptli is such 

 i liât the littoral flora can estàblish itself over their whole extent. 

 The Broads of the third group, on the other hand, possess consi- 

 perable areas of water too deep for thèse plants lo estàblish 



