Ifome.t or Tuhpfi fitrmcJ h^/ Ami^/iJ-t. 11 



Diilycll foiinil that ''' A mp/t it rite ^^ occasloniilly will reject 

 small Venetian beads and make its tube of sand, but where 

 shell.fraf!;mcnls can be procured they are preferred. Others 

 (Xicolea) support their tubes by interwcaviiipj them with 

 corallines ; while Lepr(pa irxtrix Forms a coating for its body 

 of thread-like strands after the manner of a web, as first 

 described by Sir J. Dalyell. Moreover, its ova are sometimes 

 fixed to these threads. A naked Terebella, further, can 

 p^enerally be made to unfold its coiled body by placing sand 

 in the vessel, so as to tempt it to form a new tube. 



Two species pertaining to ihe Ammocharidfe construct 

 tubes lined internally by a very tough secretion, and exter- 

 nally strenjjthened by fragments of shells. In the one 

 {Owenia Jiliformis) the shell-fragments are in many cases set 

 on edge, so that the rounded tube is bristled with them ; or 

 they are arranged in an imbricate or scale-like manner, 

 though the dense grou])ing of the fragments of shells, as a 

 rule, causes a hirsute appearance. Others are densely coated 

 with the tests of Foramiuifers. 



Amongst those which fashion homes of coarse sand-grains, 

 and the united tubes of which form conspicuous masses on 

 the sea-bottom or between tide-marks, the best known is 

 Sahellaria. One species is abundant on the eastern shores, 

 and especially at the East Rocks, while a larger form fre- 

 quents the southern waters. The busy architects collect the 

 coarse or fine sand-particles with their tentacles and fix them 

 in the walls of the rounded tube by aid of the secretion, the 

 wonderful crown of golden bristles at the anterior end doubt- 

 less performing important adaptive functions. The extensive 

 and firm masses formed by both species (for the tubes are 

 closely fixed together) must have a considerable influence in 

 protecting the tidal surface or the sea-bottom, though they 

 are disliked by the dredgers of the southern waters, who term 

 them " lioss." 



When SabeUaria spinosa constructs its tube on a shell or 

 other hard surface it is extremely dense, whereas when 

 grouped in the usual manner it is more or less brittle. Sir J. 

 Dalyell found that pounded glass and red-brick grains were 

 sparingly used, and by-and-by rejected altogether. It fabri- 

 cates its tube chiefly at night, and, like other forms, utilizes 

 the side of a glass vessel as part of the tube-wall, so as to 

 save labour. 



In alluding to the southern species [S. alveolafa), one of 

 the earlier writers on the group, viz. Dr. Thos. Williams*, 

 gave a somewhat fanciful account of the structure and varied 

 * Report Brit. Aspoc. ]8ol, p. 207. 



