452 PHORONIS 



occupied tubes are found to show that, under ordinary circum- 

 stances, a living Cerianthus occupies the interior of the tube 

 and a community of Phoronis live in its wall. This species of 

 Phoronis is never found anywhere else, and the species of Ceri- 

 antlius is very rarely found without the Phoronis." 



Ph. australis is sluggish in its movements, but other species 

 are capable of very active movement, and withdraw their 

 heads in a moment at the approach 

 of danger. A Neapolitan species, 

 Ph. kowcdevskii known to the fisher- 

 men of that place as " Ficchetelli 

 bianchi " or " Vermi di ceppa " lives 

 chiefiy on submarine posts and piles ; 

 its tubes, closely interlacing, form 

 a dense feltwork, upon which Asci- 

 dians and Sea-anemones often settle, 

 and over which Ophiurids and Poly- 

 FIG. 227. A piece of a colony of Ph. chaets creep. The tubes of this 



^S^T^uif^ 8 P<* ies < rcndered <We by the 



covered i>y particles of san.i, excreta ejected from the body, and 



they do not attach foreign substances 



to the outside to anything like the same degree as Ph. psaniiiw- 

 phila, which live in sandy places, and are termed by the Sicilian 

 fishermen " Tubi di sabbia." The feltwork of Ph. kowalemkii 

 attains a thickness of 5 to 8 cm. In each case the tube is much 

 longer than the animal it shelters, and is so entangled with its 

 neighbours, to which it frequently adheres, that it is a matter 

 of considerable difficulty to isolate it. 



The various species of Ph oronis differ a good deal in size ; 

 Cori gives the average length as varying from 1*5 to 7'9 mm. 

 in Ph. lt,ip2JOcrepia and up to 12*7 mm. (6 inches) in Ph. austral is. 

 1'robably the very short individuals of the first-named species 

 had not attained their adult stature. Ph. aiistralis has recently 

 formed the subject of a memoir by Dr. "W. R Beuham, 1 from 

 whom the following account is mainly taken. 



The length of the individuals varied from three to six inches, 

 and their diameter, which is not very uniform, averaged one- 

 eighth of an inch. At one end, which, since it bears the mouth, 

 \ve may call the oral end, is the very characteristic tentacular 

 1 Quart. J. Micr. ,SV/. vol. xxx. 1890, p. 125. 



