280 Dr. W. C. M‘Intosh 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- 
tering the mouth ofthe tube, is considered suitable, itis 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 débris, 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 débris falls to the bottom or clouds the side 
of the glass. Where the basis material is bluish shale, this 
débris 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 débris 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 
nearits tubes, it sometimes protrudes its headand anterior region, 
and aids the tentacles in dragging it towards the mouth of the 
tube, or occasionally the anterior part of the body is extruded in 
an exploratory manner ; but, as arule, theyare very shy. A free 
animal is now and then encountered, and, if im perfect health, 
* Power of the Creator &c. vol. i. p. 159. 
