CHAPTER XVI 



PHORONIS 



HISTORY HABITS STRUCTURE REPRODUCTION LARVA META- 

 MORPHOSIS LIST OF SPECIES AND LOCALITIES SYSTEMATIC 



POSITION. 



THIS interesting genus was discovered and first described by Dr. 

 Strethill Wright of Edinburgh, who in the year 1856 found 

 specimens of it living on a stone with Caryophyllia sent to him 

 from Ilfracombe. He christened the form Phoronis hippocrepia, 1 

 the generic name being apparently taken from an epithet applied 

 to lo, the specific name having reference to the beautiful horse- 

 shoe shape of its tentacular crown. Two years later a closely 

 allied or identical form was described by Professor P. J. van 

 Beneden under the name of Crepina gracilis? 



Phoronis is a sedentary animal living in " colonies," but each 

 member of the colony is distinct, and has no organic connexion 

 with the others, from which it is isolated by the presence of a 

 tube in which it lives, and into which it can be completely with- 

 drawn. The tube is formed from a secretion which probably 

 has its origin from the anterior end of the body-wall. The 

 secretion hardens and forms at first a transparent coating, but 

 it soon becomes opaque, and numerous sand particles, small 

 pieces of shell, sponge spicules, and other marine objects adhere 

 to the outside of the tubes, giving them a very characteristic 

 appearance, and doubtless serving to protect the inhabitants 

 from predatory animals. 



1 P. Pliys. Soc. Edinl. vol. i. 1856, p. 165 ; and Edinb. New Phil. Journ. vol. iv. 

 (n.s.) 1856, p. 313; Ann. Sci. Nat. 4th ser. vol. xi. 1859, p. 150; and F. D. 

 Dyster, Tr. Linn. Soc. London, vol. xxii. 1859, p. 251. 



2 Ann. Sci. Nat. 4th ser. vol. x. 1858, p. 11. 



