316 



ANNULOSA. 



The only fossils which can be asserted positively to be 

 actually portions of the bodies of Errant Annelides are the 

 minute petrifactions representing the horny jaws of Sea- 

 worms, resembling in general form and structure the jaws 



Fig. 188. Cirrhatulus grandis, an " Errant Annelide," in its living condition. 

 (After Verrill.) 



of the living Nereids. Fossil jaws of this nature have been 

 described from the Lower Silurian under the name of Nerei- 

 davus (Grinnell), and Mr George Jennings Hinde has de- 

 tected various forms of these bodies in the Silurian, Devo- 

 nian, and Carboniferous formations. 



Apart from the jaws, the integument of the Errant Anne- 

 lides always secretes chitinous matter to a certain extent, but 

 in no case does this go so far as to give rise to a regular and 

 resistant exoskeleton. There is, therefore, no ground for 

 surprise if we should be unable to point to any fossils which 

 can be properly regarded as the petrified bodies of these 

 animals. It is true that palaeontologists have often described 



