tak ZOOLOGILS T 
No. 800.—february, 1908. 
ON THE PERFORATIONS OF MARINE ANIMALS. 
By Professor McInrosu, Gatty Marine Laboratory, St. Andrews. 
In former papers* special groups of marine forms which 
perforate have been dealt with. On the present occasion a 
general sketch of the subject as represented by the various types 
of invertebrate marine animals which bore in rocks, shells, sand, 
and other media will be given. The burrowing of marine forms 
on our shores is a familiar feature to every zoologist. Moreover, 
scarcely a dead shell can be dredged from the sea-bed that does 
not present perforations of boring sponges, the slightest force, 
in well-marked cases, sufficing to break the thin superficial crust 
concealing the yellowish substance of the sponge in the interior. 
Multitudes of living Oyster-shells are affected in the same 
manner, so that the Whitstable Oyster Company and others 
have been greatly concerned about their depredations, which, 
however, are not on the whole very serious. Further, these 
perforating sponges often perform their work of destruction in 
the most regular and beautiful manner, leaving arborescent 
patterns with necklace-like dilatations, or a branching pattern 
like a Gorgonian, to mark their progress in the shell. In the 
‘same way the surface of the limestone rocks of the southern 
shores is riddled with these sponges (Cliona). So far as at 
** Ann. Nat. Hist. 4th ser. vol. ii. pp. 276-295, plates 18-20, October, 1868; 
and ‘ Marine Invert. and Fishes of St. Andrews,’ pp. 58-60, 1875. 
Zool. 4th ser. vol. XII., February, 1908. E 
