44 THE ZOOLOGIST. 
however, points out that similar urchins wedge themselves in 
most firmly if they find force applied to them, so that the wave- 
action is doubtful. 
The Annelids, again, include many forms which ceaselessly 
bore through sand (like the lobworm), earth (as in the case of 
earthworm), peat, and many soft media. Others penetrate 
aluminous shale, sandstone, limestone, shells, and various solid 
substances. Hach form, moreover, fashions a characteristic 
tunnel in the rock, so that ‘the particular borer may in most 
cases be determined, even after the dissolution and disappearance 
of the animal. They do not, however, bore in wood, and though 
pieces of telegraph-cable have frequently been forwarded with 
accompanying annelids as the depredators, in no instance has it 
been deemed prudent to connect them with the injury. Some 
authors have a different opinion, but the misapprehension has 
arisen simply from the presence of formidable calcareous jaws in 
annelids found lurking in holes which have been drilled by other 
forms. In short, it is a revival of the ancient notion which, 
assuming the shells of Teredv to be its teeth, credited it with the 
habit of eating its way into timber. In the same manner it 
has been supposed that Polydora and other boring annelids 
have found their way between the valves of Oysters, and subse- 
quently have been enveloped by the shelly secretion of the 
mollusk. 
Certain members of a group somewhat allied to the Annelids— 
viz. the Gephyreans—also bore in calcareous substances, such as 
shells and limestone rocks, as well as more generally in mud and 
sand. Such include the little Sipwnculus of the British shores, 
and which at St Andrews makes cavities in sandstone; Bonellia of 
the more southern waters; and Thalassema, which Dr. Farran* 
found in limestone near Dungarvan, in company with Gastro- 
chena. Other members of the group are partial to boring in sand 
and tough clay, or muddy clay. 
Certain forms allied to the Polyzoa jemand perforate cal- 
careous rocks. Thus Phoronis, a form which in its larval state 
has relationship with higher types, has been found in tunnels in 
chalk, and so far as could be made out it appeared to have 
formed them. It is interesting that Phoronis often occurs in 
* Ann. Nat. Hist. 2nd ser. vol. vil. p. 156. 
