NATURAL HISTORY SOCIETY OF GLASGOW. 33 



lumps of which Professor Thomson speaks, was caused by the 

 annehd, as in the previous instance. 



The examples No. 3, also Terebella, have added to their clay 

 tubes a few chips of shells and other hard materials, as if to 

 give support to the structure, but they do not belong to the same 

 species. 



The specimen ISTo. 4 is too fragmentary to be determined. It 

 is less remarkable for the order in w^hich the materials are builtj 

 than for the selection it makes of the particular materials used* 

 The sand, amongst which the tubes are found at a depth of 60 

 fathoms, is of a yellowish-green tint, and is intermixed with a fcAV 

 grains of garnets and black sand. The specimens of the tubes 

 shown are placed on the sand in their natural condition; and a 

 decided contrast between the native sand and that of the tubes is 

 seen. This difference of shade will be found on close examination 

 to arise from the animal having selected from the general material 

 chiefly those grains most brilliant and conspicuous in colour, to 

 adorn its subaqueous habitation. 



No. 5, Pettco imsilla, is made up of grains of sand of various 

 sizes, which are fitted one into another with extreme neatness, 

 and are securely held together by clean lines of white cement, 

 anticipating our finest specimens of rubble work. 



No. 6, Pedmaria belgica (Pallas). In this the building materials 

 are much finer, and of a more uniform size, than in the previous 

 cases. Nothing can exceed the manner in which these grains 

 are put together, far surpassing the finest mosaic work. In this 

 case the interbinding cement adds greatly to the beauty and 

 delicacy of the structure. The cement has also the priority over 

 all art compositions, inasmuch as it sets or hardens and remains 

 insoluble under water. 



No. 7, Owcnia filiformis (D'Chiagii). The tube of this animal 

 in its entirety tapers towards both ends. The taper is longest 

 posteriorly, and is beautifully imbricated along its whole length, 

 each piece being selected and arranged to suit the swell and 

 decline of the taper. There are other species that follow the 

 same style, but differ considerably in the execution of the work ; 

 as in No. 8, a doubtful species, which is much more coarse and 

 rugged, and has a more abrupt taper. 



No. 9, probably Terebella. The style and purpose of the 

 -woTkicormshi-p of the tube in this case are not easily understoodj 



VOL. III. c 



