1885-86.] Edinburgh Naturalists' Field Cljib. 315 



notum Corallina officinalis (growing abundantly in rock-pools-a 

 beautiful object), Polysiphonia nigrescens and P. fastigiata. The 

 arger Seaweeds, as Fucus and Laminaria, will always repay inves- 

 tigation for attached to them are frequently found various forms 

 of Zoophytes and minute MoUusca, as well as epiphytic Al-a^ • 

 while under their heavy drapery many of the finer Seaweeds fove 

 to luxuriate. On the sides of pools, and overhung by these laro-er 

 forms, there were found numerous patches of microscopic Alo-aj bear- 

 ing Diatoms in great abundance. The tufts gathered, when exam- 

 med under the microscope, were found to be mostly Polvsiphonia 

 mgrescens and Ceramium rubrum, covered with such Diatoms as 

 bchizonema Grevillei and Synedra gracilis. Specimens of these 

 are shown under the microscope. 



We had now been occupied for about two hours in our investiga- 

 tions, and had we waited a little longer, the ebbing tide would 

 have permitted an examination of the rock-pools on the seaward 

 portion of the reef, where other treasures would doubtless have 

 been found. But snow coming on, and darkness beginning to fall 

 we turned our faces homeward, carrying away sufficient material 

 tor several mstructive " evenings at home with the microscope." 



II. JOPPA. 

 By Mr JOHN ALLAN. 



A contingent of the Club visited Joppa rocks on the afternoon of 

 baturday, 30th January, and met with very much the same " finds " 

 as on the Granton excursion. The only shell-fish observed, in addi- 

 tion to those got at Granton, were Chiton marginatus and Pholas 

 dactylus The latter burrows so deeply in the rock, that onlv the 

 mouth of the circular hole it makes can be seen, and any attempt 

 to dig it out simply results in its breaking to pieces. It has lono- 

 been a mystery how so frail an animal can bore through rock and 

 other hard substances, just as it is equally puzzling how a soft 

 Sponge {Chone cdata) can drill holes through Oysters and other 

 thick shells.i Empty shells of Cockle, Pecten, Solen, and Turri- 



1 The Pholas is not the only boring Mollusc, although it is the one regarding 

 which probably, most has been written. Various theories have been mit 

 forward to account for its boring powers,-such as the elaboration of an acid 

 secretion, and the presence of flinty spicules on the "foot." But the W 

 modusopercvmU has in all likelihood been now discovered, from keeninc, s,w 

 !?f '' /L?^"''^ ^'l"f"* ^"<^ watching them at work. By means of the fleshy 

 foot, the extremely hard shell is pulled constantly backwards and forwards 

 thus acting as a rasp or file ; while the siphon-tube at the opposite extrem tv 

 ejects a continuous stream of water, which keeps the "tunnel" that is bS 

 hollowed out always damp, and at the same time carries away the abraded 



