86 MISCELLANEOUS. 



Perhaps they washed the shell until coming to a surface, as the aper- 

 tures are all exposed. The animal is lively and active ; very timid, and 

 withdrawing into its shell on the slightest motion. When undisturbed 

 it remains with its numerous plumes unfolded, at the mouth of the shell. 



Apparently they are of two species : the plumes of the one black 

 and white, of the other pink. 



A portion of rock, with several shells, having been out of water four 

 days, I suspended it by a thread among some water : and, in an hour, 

 I thought one animal was protruding itself ; but, after longer time, this 

 seems doubtful. Small bubbles of air escaped from different apertures. 



These creatures are generally of a greyish or greenish colour in the 

 posterior part, and of a firm gelatinous consistence. Several spines are 

 visible on each side of the portion corresponding in situation to the 

 thorax. Is their use to retain the animal in its shell ? 



At Queensferry, this animal is seen on the rocks, but it is not plen- 

 tiful. Perhaps the species is different : as it seems solitary, or in very 

 small societies, and the shell is much larger, and very white ; but I have 

 not made particular observations on it. 



On the 29th of September 1810, I took several of these animals, of 

 different sizes, on stones at Queensferry. One was still alive on the 27th 

 of May 1811, when it was lost in the confusion of moving from one 

 house to another. I could not discover their food. 



PLATE XX. 



FIQ. 1. Pecten covered with Serpula. 



2. Oyster covered with Serpula. 



3. Specimen removed from the shell. 



4. Tho same, magnified. 



5. Solitary specimen. 



6. Branchial plume, magnified. 



