280 Dr. W. C. M'Intosli on the Boring of certain Annelids. 



seized and passed along the tentaculum, and apparently carried 

 to the mouth*". If the particle of sand, for instance, after en- 

 teringthe mouth ofthe tube,is considered suitable, it is by-and-by 

 pushed out with the snout, and arranged on the circumference 

 of the tube with the glutinous secretion. Occasionally the 

 proximity of other tubes affords an opportunity for abstracting 

 particles therefrom, as well as causes frequent collisions with 

 neighbouring tentacula, especially apparent when two take 

 possession of the same prey. Now and then a small mass of 

 mud and sand may be seen travelling outwards from the tube 

 along the tentacle, to be dropped at some distance. Quantities 

 of debris, again, may sometimes be observed issuing from 

 both apertures; and in those vessels in which the animals have 

 been vigorously at work on new sites, heaps of minute grains 

 of sand or altered shale are grouped on the flat surface around 

 the tubes ; or if these are elevated in the vessel and project 

 horizontally, the debris falls to the bottom or clouds the side 

 of the glass. Where the basis material is bluish shale, this 

 debris has a brownish colour, and the particles assume a some- 

 what definite ovoid shape, so that the heaps have a peculiar 

 miliary appearance. The alteration in the colour in this case 

 is interesting, showing that in all probability the masses have 

 passed through the digestive tract of the Annelid. Moreover 

 we may be fairly warranted, from the appearances, in assuming 

 that at least some of the constituents of such heaps are the 

 results of the boring, and not all due to the seizure of external 

 particles from (in this case) the smooth surface of the shale. 

 There was nothing peculiar in the instance of the sandstone, 

 whose loose debris after boring resembled the grains of sand 

 removed from the mass. 



The benefits of a tube superadded to the gallery in the stone 

 are apparent ; for the tentacles are thus enabled to take a longer 

 sweep through the surrounding water for the capture of minute 

 structures while the delicate body remains protected. More- 

 over a field of competition is opened up to these social Anne- 

 lids, in which it must at least occasionally occur that the best 

 and most rapid builder of these tubes is placed under more 

 favourable conditions for existence than those with shorter tubes 

 or those confined to the dead level of the rock or shell. 



When the animal happens to find a large mass of loose material 

 near its tubes, it sometimes protrudes its head and anterior region, 

 and aids the tentacles in dragging it towards the mouth of the 

 tube, or occasionally the anterior part ofthe body is extruded in 

 an exploratory manner ; but, as a rule, they are very shy. A free 

 animal is now and then encountered, and, if in perfect lieaUh, 



* Power of the Creator ^c. vol. ii, p. lOl), 



