348 THE ZOOLOGIST. 



All along the shore were numbers of boulders which had been 

 perforated through and through by the little Isopod crustacean 

 Sphceroma, assisted here and there by a boring mollusc. These 

 little creatures form a very powerful factor in the disintegration 

 of the rocks, as, after they have driven their galleries through, it 

 is quite an easy matter for the sea to do the rest. As com- 

 mensals in the burrows of these Isopods, I have observed many 

 other small crustaceans, several species of small fishes, including 

 the Common Eel (Anguilla australis), and also a brown-coloured 

 Araneid. This last — of which individuals were numerous — 

 remains in the burrows even when the tide rises and floods them, 

 and it may be seen moving about beneath the surface clothed in 

 a tunic of air-bubbles. 



While speaking of the seashore, I must mention something 

 connected therewith which at once claims the naturalist's atten- 

 tion, and that is the zones which each animal (or set of animals) 

 occupies. Taking a typical flat, and starting from the top, we 

 would first come to a sandy zone, slightly above high water. 

 This is inhabited by the beautiful " Swift-footed Crab" (Ocypoda 

 cordimana), a small grey Isopod ; and, in the event of there being 

 decaying animal or vegetable matter, many specimens of the 

 Common Sandhopper (Talorchestia quadrimana). Then, lower 

 down, there is a zone just lapped at high water, about which are 

 strewn clean stones (i. e. stones not overgrown with Algae). 

 Under these stones are to be found many interesting and exceed- 

 ingly agile Crabs (Cyclograpsus Lavauxi). Going still lower, we 

 come to a belt consisting of a mixture of sand and mud. On — 

 or rather in — this we find the bright-coloured, martial-looking 

 "Soldier Crab" (Mycteris longicarpus) ,* and an exceedingly 

 fragile Callianassa. Going beyond this again, we arrive at a 

 zone which is only just above low-tide mark. This is composed 

 of dark evil-smelling mud, with occasionally small Algae-covered 

 boulders strewn sparsely over its surface. On the stones them- 

 selves (amongst the Algae) we find some tiny Crabs (Hymenosoma 

 varium and Pore ellana dispar). Underneath will be found others 

 and larger species, viz. Chasmagnathus Icevis, Sesarma erythro- 

 dactyla, and occasionally Pilumnopeus serratifrons. In the mud 



* For further information regarding these crustaceans, cf. author's 

 " Notes on the Habits of some of the Australian Malacostracous Crustacea " 

 (Zool. May, 1898). 



