MARINE FAUNA OF ST. ANDREWS. 
GO 
shells and tunnels of the mollusks themselves. The 
epidermis of the latter in each case would likewise suffer. 
IT. That the holes are made by rasping effected by siliceous 
particles on the foot of the mollusk (Hancock), by grains 
of silex from the exterior (Bryson), by the foot in 
some way (Dr. Fischer), by chitine in the cirripedes 
(Darwin) and gephyreans and the bristles of the annelids. 
This explanation is not borne out by the case of the 
sponges, by that of the Bryozoa, and certain cirripedes ; 
moreover such siliceous particles are rare in boring 
mollusks. 
III. That the excavations are due to ciliary currents, aided 
by rasping (Garner). 
The currents may assist, but seem to be insufficient to 
account for the borings of any group. 
IV. That the perforations are produced by a chemical solvent: 
Gray, Osier (for Saxicava), Drummond, Cailliaud, Mantell, 
Thorent, Reeve, Bouchard-Chantereaux, Spence Bate, 
Darwin (for Verruca ), E. R. Lankester, and Parfitt. 
This will not explain the borings in wood, aluminous 
shale, gneiss, granite, sandstone, and wax. It is interest¬ 
ing, however, as my friend Mr. Ray Lankester has spe¬ 
cially shown, that shells and calcareous rocks are much 
affected by burrowing marine animals. 
V. That the borings are the result of a secreted solvent and 
rasping action (Thompson and Necker). 
It seems improbable that the solvent should vary with 
the nature of the rocks attacked. 
VI. That the perforations are caused by a macerating or simple 
solvent action of the foot in mollusks (Sellius, Deshayes, 
and Gwyn Jeffreys). 
It is doubtful if this would be supported by the action 
of the sponges, Bryozoa, annelids, gephyreans, and cirri¬ 
pedes. The stria? in certain of the tunnels of the shell¬ 
fish are also somewhat at variance with this notion. 
The most interesting species in regard to rarity are Lima 
svhauriculata and L. Loscombii , which come from deep water, 
the characteristic Lima Mans of our southern and western 
