316 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



diameter. It is lined with a tough whitish secretion. 

 Some of the spines are curved, others straight and varying 

 from 1 inch to 1\ inches in length. They are hollow, 

 and formed of a white porcellaneous material, probably 

 the same as the lining of the tube. At the base they are 

 much swollen, the hollow bulb being filled with fine sand, 

 similar to the coating of the main tube. The porcel- 

 laneous coating is very thin, and drawn out to a fine point 

 which is transparent, the internal tapering cavity being 

 visible, and closed at the tip. The method by which 

 these spines were actually formed is, of course, unknown. 

 They are not socketed on to the main tube, but are very 

 firmly attached to it by the parchment-like material with 

 which the spines are coated. Numerous small pieces of 

 this material project at intervals outside the tube. In two 

 instances these are triangular in form, -| inch wide at the 

 base, where attached to the tube, and \ inch long, tapering 

 to a point. 



These strips suggest, I think, a probable method of 

 formation of the spines. It is very likely they were 

 formed at the mouth of the tube as foundations for spines, 

 and were afterwards abandoned. Two spines actually in 

 this position are shown in fig. 9, one of them being in fact 

 a continuation of the edge of the tube. Like the valves 

 in the tube of Hyalinoecia, these structures are most 

 probably formed by the mouth of the worm, the sand 

 being also thereby collected and secured in position by the 

 longitudinal folding of Hie triangular strips, which are 

 then, by further additions of the secretion, worked up into 

 the long spines shown upon the figure. For further 

 information, reference should be made to the "Challenger" 

 Report, vol. xii., pp. -°)25 and 32H. 



As regards defensive mechanism, it is well known that 

 many species of tubicolons worms secure themselves by 



