136 



THE SEA-SIDE AND AQUARIUM. 



spreads open like a fan. In the centre a kind of 

 conical plug or stopper appears, around which the 

 feathers seem to have been rolled. 



The sense of vision which the Serpula possesses is 



COMMON SERPULA. 



extremely acute, and this is the more curious from the 

 fact that all naturalists have hitherto failed to discover 

 any eyes.'* Still, that these organs exist, is manifested 

 by, among other proofs, the fact that if a hand be 

 passed over the tank, the fan instantly disappears. 

 After a while, this extreme sensibility, however, be- 

 comes dulled by familiarity with shadows cast by 

 passing objects, such as Blennies, &c. 



* M. A. Quatrefages thinks he has discovered eyes upon the 

 branchiae of the Sabellse. Vide " Mag. Nat. Hist./' 1850. 



