92 
ORGANIC DEPENDENCE AND DISEASE 
To a flattened tube with raised edges, giving the sugges- 
tion of a distinct loop with the branches connected by a 
thin diaphragm, we have on a previous occasion applied the 
name Caulostrepsis taeniola. So far as onr present knowl- 
edge goes this has been seen only in stropliomenoid brachio- 
pods from the Lower Devonian of the Rhineland. 
Fig. 77. Palaeosabella prisca in a valve of the brachiopod Leptostrophia. From 
the Grande Greve limestone (Lower Devonian); enlarged. 
Finally, it is worthy of note that the host-shells receive 
these boring worms in various ways. Sometimes the para- 
site starts at one surface and bores straight across to and 
through the other surface. Again a number of worms may 
commence their attacks simultaneously at the growing edge 
of the shell and while they bore parallel to, and within the 
shell surfaces, the shell grows on outward beyond the circle 
