PRESIDENTIAL ADDRESS. 35 



A remarkable expression of the landward migration of 

 the littorinoids is Melaraphe scabra, whose special haunt 

 is the leaf of the mangrove (fig. 3). More than two cen- 

 turies ago Rumphius, who saw it in the Moluccas called it 

 Buccinum foliorum in allusion to this habit. The variety 

 filosa was gathered in November 1847 by MacgiJlivray on 

 the leaves of Mgiceras at Port Curtis. 1 A depauperated 

 form called luteola by Quoy and Gaimard occurs on Avi- 

 cennia about Sydney and Port Stephens. Its tropical 

 companion Cerithidea which perches on the boughs and 

 twigs of the mangroves does not descend so far south. 



Exposed to the hottest sunshine 

 and watered only by spray or by the 

 highest tide, Tectarius pyramidalis 

 (fig. 4) creeps furthest in the ascent 

 of the ocean rock beach. Kesteven 

 observed that its osphradium has 

 degenerated so as to be almost use- 

 less, he thought that the animal was 

 Fig. 4. Tectarius pyra- protected against evaporation by an 



midalis, the highest climber . 



from the sea on the ocean abundant secretion of mucous, seal- 

 beach, magnified. ing up the mouth f the shell.* 



In the estuary the boundaries of land and sea overlap, 

 though a wide neutral zone separates them on the rocky 

 ocean beach. 



To the amphibious fauna of the transition area, the 

 mangrove swamp contributes the Auriculidse, the rocky 

 beach supplies the littorinoids and the ocean sand beach 

 has for its representatives the swift-sand-crab Ocypoda 

 (fig. 8) and the sand-hoppers of the family Orchestidse. 



1 Eumphius, Amboinische Eareitkamer, 1705, p. 98; Forbes, Voy. 

 Rattlesnake, ii, 1852, p. 362. 



2 Kesteven, Proc. Linn. Soc. N.S. Wales, xxvii, 1903, p. 621. 



