140 
The South Australian Naturalist 
EXCURSION TO MARINO, AUGUST 9, 1924.— A part^ 
visited Marino, under the leadership of Mr. George Beck. The 
cliffs below the station proved a better hunting ground for wild 
ffowers than might have been expected at this time of the year. 
Exposed as they are to the cold winds from the sea the plants 
are stunted in habit. One of the best illustrations of this is the 
Spoon Wattle (Acacia obliqua) which here forms only low bushes 
little more than a foot in height, though its natural habit is a 
small tree, it was found to be blooming profusely, the yellow, 
fluffy balls contrasting with the dark green leaves. The yellow 
ilowers of V elleya paradoxa, with its curious little “taik’ on the 
flowers was abundant. This ffower should prove easy of cultiva- 
tion. Plants continue to bloom almost all the year. Two 
orchids were secured, the beautiful blue Thelymitra aristata 
(“Scented sun-orchid'') and the smaller Diuris palustris. Two 
varieties of wattles were in bloom, Acacia obliqua and A. pycnan- 
tha, the latter in sheltered gullies, which also gave the necessary 
protection to Lotus australis, Dodonaea viscosa (“Hop bush”), 
and Scaevola aemula. In places the wild lilac, Swanisona lesser- 
tijolia, was plentiful, and here and there the Scarlet runner (Ken- 
nedy a prostrata) was seen. Senecio lautus_ blossomed on the 
steep cliff sides, where also a few specimens of Hakea ulicina 
were found in flower, and a few plants of Grevillea lavandulacea. 
These were the chief plants secured during the afternoon. At 
the end of a pleasant ramble Air. G. Beck entertained the party at 
afternoon tea, and the party caught the train at Marino station. 
LECTURES, “WOOD AND ROCK-BORING MOL- 
LUSCS,” BY AIR. W. I. KIAIBER, AND “SOAIE COMMON 
MINERALS,” BY DR.' C. FENNER, F.G.S., MAY 29, 1924.- 
Alr. Kimber explained that these molluscs bored into wood and 
rock, not to obtain food but to protect the soft body^ of the mollusc 
against injury or attack. Alost rock and timber borers belonged 
to the family Pholadidae, a mollusc which makes a very hard, but 
brittle white shell, with projections like the teeth of a rasp. When 
a suitable rock was found the young Pholas attached themselves 
by the foot muscles, and bored the hole, which it could not leave. 
It was generallyadmitted that the work of boring was done by the 
muscular foot, aided by^ the shell. Observation showed that the 
foot was used as a bradawl. The hardest rocks were pierced in 
this way. In the Bay of Naples the hard porphyry columns of 
the Serapeum had been penetrated by the agency of these tiny 
molluscs, and the hardest pearlshell exhibited its handiwork in the 
“blister” pearls by which the oyster strove to remove the irritation 
resulting from the unwelcome attention of the borers. These 
