20G 



estuaries sheltered from wave disturbances ; (2) those which 

 live on the seashore exposed to wave and tidal action; (3) 

 those living at the sea-bottom outside the tidal strand. The 

 species are not only restricted in their range in depth, but also 

 in respect to habitat in accordance with their structure. 



Littoral Life. — 1. Mollusca living between tide-marks in 

 sheltered bays and estuaries. — Exemplar stations are the Port 

 Creek and the estuary of the Onkaparinga. The tidal strand 

 is here usually composed of mud often clothed with a green 

 mantle of Zostera ; whilst pools at the upper limit of the tide 

 furnish a vegetable growth of Lepilcena Preissii, amongst which 

 live Pomatiopsis striatula, Tatea o'uHlahris, Bithynella Victories; 

 whilst at the extreme upper limits of ordinary tides, sheltering 

 under Salicornia, Suceda, Sfc, the pulmonates Ainpullarina 

 Quoyana, A. fragilis, Alexia meridionalis and Pythina ciliata; 

 and Risella melanostoma, Assiminea sp. Between tidal-marks 

 the majority of the gastropods are vegetable feeders — Bittiiim 

 granarmm, B. Laivleyanum, B. turritumy Risella melanostomay 

 Trochochocolea tcBniata, Acmcea conoidea. The only common 

 carnivorous gastropod is Tropon australis. Here is the chief 

 habitat of the bivalves Tellina deltoidalis, Anapa ctineata, Chione 

 aphrodina and Modiola flavida — the three former burrowing by 

 means of their foot, the last forming a nest for itself in the 

 soft mud. 



2. Mollusca living on the tidal strand of the exposed coast. 

 — These may be considered under two heads, viz., (aj Those 

 living on rock or other firm foundation, and fh) those living 

 in sand or mud. 



fa) Those living on rocks. The methods by which they 

 resist the attacks of waves are various, some of which are well 

 known. Examples of permanent attachment are the oyster and 

 mussel, of temporary attachment, the limpet and chiton, and 

 of boring, the pholas. In addition, there is a large number 

 deficient in powers of attachment, which find protection from 

 the waves by secreting themselves under large flat stones or in 

 rocky crevices. Living on rock, as it were between air and 

 water, and where moistened only by the spray of the breakers, 

 occur the pulmonate snails Marbiula paiula and Truncatella 

 scalarina^ and the branchiferous snail Littorina Mauritiana; 

 whilst the minute bivalve Lasea rubra nestles in crannies of the 

 Tock-face. The gastropods living on rocks exposed to breakers 

 have almost without exception shells of an ovate or rounded 

 outline, shortly conical or more or less flattened — shapes best 

 adapted to resist the action of the waves. A list of the com- 

 moner species was given. The carnivorous species are few, the 

 commonest ones are — Trophon FRyidersiy Pupura sitccincta, 

 Ricinula Adelaidensis^ Cominella costata, and C. alveolata. All 



