310 APPENDIX II 



Beetles are especially common on the sea-shore, and 

 Keys (191 8) in enumerating the species found on the South 

 Devon and Cornwall coasts has classified them as follows : 

 (a) Maritime species : those covered by the sea for a 

 considerable time during the ebb and flow of the tide ; 

 8 species, (b) Sub-maritime species : dwellers at high-tide 

 mark or thereabouts and subject to occasional wettings ; 

 inhabitants of brackish pools and wet places in salt marshes ; 

 54 species, (c) Coast species which are, as a rule, safe from 

 the reach of high tide but are peculiar to coast plants or 

 live under stones, on wooden piles, and in fresh- water oozes 

 on the cliffs ; 89 species. 



Many shore beetles belong to the predaceous Carabidae 

 and, in addition to feeding on animal refuse, may prey upon 

 sand-hoppers. They may burrow in the sand at low tide 

 or lie motionless under stones and in this way are able to 

 resist short immersion. Several are wingless and in one 

 case at least, that of Aepus marinus, there is very marked 

 specialisation for an amphibious existence. In addition 

 to being wingless and to having its body covered with 

 hairs, Aepus is provided with a large pair of air-sacs in its 

 abdomen which supply the respiratory needs of the animal 

 when submerged. At low water Aepus may be seen run- 

 ning about on stones, sponges, and weeds, and is thought 

 to prey upon the Gasteropods Rissoa and Lascea (Miall, 

 op. cit.). 



The sea-shore flies (Diptera) are hardly less numerous 

 than the beetles. " Flesh-flies " (Sarcophaginae) are promi- 

 nent and the " black-fly " {Coelopa frigida), which is not 

 unlike a house-fly in appearance, is also common ; while 

 in addition to the adult flies, numbers of their maggots 

 may be seen feeding among the jetsam. Both larva and 

 pupa can withstand short immersion. Miall {op. cit.) 

 mentions the larvae of the fly Arctora cestuum as feeding 

 upon stranded bladder- wrack (Fucus vesiculosus). The 

 adult flies, which occur in summer at the water's edge, are 

 larger than Coelopa and of a lighter grey in colour, while the 

 larvae are covered with short hairs. Other prominent flies 

 which frequent the water's edge belong to the Dolicho- 

 podidae and are readily distinguished by their brilliant, 

 metallic coloration. Midges are numerous above rock 



