370 - Miss B. Lindsay on th^ 



on the east side — that is, on the side looking towards the 

 open sea. The material removed is chiefly shale, but the 

 sand-tone (calciferous sandstone of Geikie) is also attacked, 

 and the gradual removal of this bulwark admits the force of 

 the sea to the middle of the bay, wiiere much destruction of 

 the cliff-line has taken place within recent years, both 

 immediately in front of the Gatty Marine Laboratory and 

 all along the bay. There is urgent need for a small break- 

 water, to replace the protecting rock which is being 

 destroyed.' 



Another boring-ground is situated at the opposite side of 

 the bay, in the rocks near the Beacon, at the end of tiie pier. 

 The burrows are found in both shale and sandstone, and 

 there are places in which the animals appear to have begun 

 to work upon sandstone and to have made their way down- 

 wards into an underlying bed of shale. It is notewortiiy 

 that this boring-ground is washed by fresh water, for the 

 stream which runs into the sea from St. Andrews harbour 

 passes over the eastern border of these rocks. Great 

 denudation has probably taken place here within tlie 

 historic period ; for there is no reason to doubt the truth of 

 the local tradition, which states that the earliest church in 

 St. Andrews was built here, on land now washed away. 

 Here, again, the boring-ground lies to the eastward side of 

 the place of sea-encroachment. Only the upper border of 

 the borino-grounds is accessible, and that only at the lowest 

 tides. Most of tiie destructive work accomplished by the 

 Pholadide borers takes ])lace below the littoral zone ; unseen, 

 and, by the ordinary observer, unsuspected. 



On the West Sands, and at the mouth of the Eden, 

 Zirjihcea attains a larger size and possesses fewer and 

 weaker ridges — a condition implying tliat it bores in softer 

 material, probably mud and sand. The animals are rarely 

 seen alive, but many shells are washed u}) after a storm. 



Darnea {FItoias) Candida occuis similarly on the West 

 Sands, and is found occasionally in the rocks below the 

 Cii-stle. Comparatively rare at St. Andrews, it is of little 

 local importance as an agent in the destruction of rocks. 

 During blasting-operations in 1896, however, many speci- 

 mens were thrown up on the beach, a fact recorded by 

 Professor Mcintosh in the ' Zoologist ' for February 190S. 



Tapes pid/asira, which frequently inhabits the old burrows 

 o^ Zirp/icea, has sometimes been mistaken for a borer. My 

 observations confirm the statement of Gwyn Jeffreys, that 

 t!ie shells are frequently distorted by having been confined 

 in a burrow. This is a sufBcient proof tliat the animals 



