THE FAUNA OF THE SALCOMBE ESTUARY. 169 



and the mouth of the harbour on the eastern or western side, but are 

 either not found or are much less numerous on the Salstone : — 



Oi^hiocnida brachiata. [ Lanice conchilega. 



Echinocardiura cordatum, with > Gebia stellata. 



Montacuta ferrnginosa. Soleii marginatus. 



Synapta inhserens. Pecten maximus. 



Neijhthys caeca. Venus striatula, 



Goniada maculata. Lucina boi'ealis. 



Amphitrite Edwardsi, with Lepi- Aplysia punctata. 



dasthenia argus. 



On the other hand, certain species are abundant on the shore at the 

 Salstone which are absent or are much less numerous on the banks 

 near the mouth of Salcombe Harbour, Amongst these are : — 



Hymeniacidon sanguineum, 

 Sagartia bellis. 

 Prosthecerteus vittatus. 

 Nereis longissima. 

 Notomastus latericeus. 

 Branchiomma vesiculosum. 

 Myxicola infundibuhxm. 



Melinua adriatica. 

 Inachus dorynchus. 

 Tapes puDasti'a. 

 Scalaria communis. 

 Bulla hydatis. 

 Phallusia mammillata. 

 Ascidiella aspersa. 



Sabella pavonina. | Morchellium argus. 



Amongst the Foraminifera Rotalia hcccarii is the prevailing species 

 on the Salstone, whilst its place seems to be taken by Folystomella 

 crispa and Truncatulina lobatula on the zostera banks and sand near 

 the mouth of the harbour.* 



On comparing the two lists just given, it will be seen that the 

 majority of the species are animals which adopt either the fixed or 

 burrowing habit, and the nature of the soil or bottom-deposit will 

 in many cases be the determining factor in the difference of distribu- 

 tion observed. In the lower parts of the harbour this is almost entirely 

 fine sand, whilst on the Salstone it is either muddy gravel or fine mud 

 The increased amount of wave-action near the mouth of the harbour is 

 also a factor which must be taken into consideration, though its action 

 is doubtless principally indirect in preventing the deposition of mud. 



As has been pointed out elsewhere, it seems probable that the 

 difference in the density of the water in the two localities is not very 

 great, and that even at the Salstone we are still dealing with a marine 

 rather than with a brackish-water fauna. The amount of suspended 

 mud in the water, on the other hand, will be very much greater in the 

 higher part of the estuary. 



* Pohjstomella crispa is very alnuidant on the zostera in Cawsand Bay, near Plymouth, 

 and can he obtained in quantity by rubbing the zostera on a sieve, a mode of obtaining it 

 which is due to Mr. J. J. Lister. [E. J. A.] 



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