180 Reviews— Marine Boring Animols 



noticed in other districts during the last decade. By early geologists 

 this close genetic connexion was not credited, but its acceptance 

 has led to the enunciation of theories which have yet to be developed 

 on physico-chemical lines as a branch of the petrogenesis. There is 

 no field of research which affords such scope for original work 

 as the origin of lodes in their connexion with a consolidating magma, 

 and particularly this question of the definite order of arrival of the 

 minerals as an accessory function of it. As a whole the monograph 

 is a complete treatise on the occurrence and production of tin ore 

 as far as it is possible to make it in a few pages, and it is the best 

 resume of the subject yet published, the brief geological accounts 

 being particularly good. D. A. MacAlistp:r. 



Marine Boring Animals Injurious to Submerged Structures. 

 By W. T. Calman. British Museum (Natural History), 

 Economic Series, No. 10. London, 1919. Price Is. 

 rpHIS work, issued as a guide to an exhibit in the British Museum 

 -*- of the more important marine animals which are so destructive 

 to timber and stone, will be of considerable interest to geologists. 



Of the Molluscs which bore into wood a full and valuable account 

 is given of the shipworm Teredo navalis, in which the boring is done 

 by means of rows of fine sharp-pointed teeth on the front of the 

 valves. Brief mention is made of other wood-boring laniellibranchs — 

 PJiolas, Martesia, Xylophaga. Next in importance to the shipworm 

 as a destroyer of timber is the small Isopod Crustacean, known as 

 the Gribble {Limnoria lig'norum) ; other Cru^stacea which bore into 

 wood are the Amphipod Chelura terebrans and the Isopod Sphceroma 

 terebrans. 



Animals which bore into rocks are more numerous than those 

 which bore into wood, and include Sponges, Echinoderms, Worms, 

 Molluscs, and Crustacea. Pholas is believed to make borings 

 mainly by the rasping action of the shell which is provided with 

 rows of spines or teeth towards the front edges. Petricola 

 •plioladiformis, although belonging to quite a different family (the 

 Veneridse), is remarkable for the close resemblance of its shell to 

 Pholas Candida. Lithophaga {LitJiodomus) bores in calcareous rocks 

 by chemical means, an acid secretion being formed by a gland 

 in the mantle. Saxicdva rugosa is found mainly in limestones, 

 and the boring is probably effected by chemical means. TRe 

 principal Crustacean which bores into rocks is the Isopod Sphceroma 

 quoyana, found on the coasts of Australia and New Zealand, where 

 it burrows in soft sandstone and claystone. Other rock-boring 

 animals described are the Polychaete worm Polydora and the Sponge 

 Cliona celata. 



In connexion with rock-boring organisms attention may be 

 called to a recent pajjer by Professor T. J. Jehu, dealing with the 

 subject from the point of view of coast erosion [Scottish Geogr. 

 Journ., xxxiv, January, 1918). 



