NATURAL HISTORY — ZOOLOGY. 227 



the decomposing stones of our new Houses of Parliament, or simply 

 a thick coat of tar or paint, continually applied, which would not 

 only destroy any adult ship-worms then living hi the wood, but pre- 

 vent the ingress of the fry. The Teredo never commences perfora- 

 tion except in the larval state. 



A Committee of the Association has been formed, at the suggestion 

 of Mr. Jeffreys, to inquire and report as to the best mode of pre- 

 venting the ravages of Teredo and other animals in our ships and 

 harbours. 



Professor Van der Hoeven referred to the fact, that the ship-worm 

 attacked ships more one season than another. In 1S58 they com- 

 mitted great ravages on the ships of Holland, and a committee of 

 the Dutch Academy of Sciences was appointed to investigate the 

 subject. 



Professor Verloren stated that the species which attacked the ships 

 of Holland was Teredo navalis ; but the species in Norway, France, 

 and England, were sometimes different. 



Sir W. Jardine expressed his surprise that the Government had 

 not appointed a committee to investigate the subject. 



Professor Huxley stated that probably the House of Commons had 

 had too much experience of the utter inutility ot attempting to stop 

 a bore, to undertake the subject. 



Dr. E. P. Wright exhibited some specimens of a new genus of 

 Teredine, which he called Halidaia. It occurred near Feruckpore, 

 in Iudia, and inhabited perfectly fresh water. It was one of the 

 largest species known, and the first which had been found in fresh 

 water. _____ 



BORING OP THE PHOLADID/E. 



Mr. Alexander Bryson has read to the Royal Society of Edin- 

 burgh a communication referring to the various theories advanced to- 

 account for the Boring of the Pholadidre in rocks. 



The first hypothesis, which supposes that the molluscs perforate 

 by means of the rotation of the valves acting as augers, he disproved 

 by exhibiting old individuals of the Pholas crispata with the den- 

 tated costse as sharp as in any young specimen. That these animals 

 bore by silicious particles secreted by the foot, as suggested by Mr. 

 Hancock, has been disproved by microscopic observation ; and that 

 currents of water set in motion by vibratile cilia, seemed also insuf- 

 ficient to account for the phenomenon. 



Another theory supposes that an acid is secreted by the foot, 

 capable of dissolving the rock. This the author showed was not 

 tenable, as the strongest Nordhausen sulphuric acid fails to dissolve 

 aluminous shales and Silurian slates ; and also that any such acid 

 secretion would act more readily on the valves themselves. 



From many experiments on the cutting of hard silicious substances 

 the author found that the softer the substance was in which the 

 cutting material was impacted, the greater the amount of the work 

 done. He was thus led to the conclusion that the pholadidse bore 

 with the strong muscular foot alone, and that they obtain the silica 

 P 2 



