TEREBELLA. 201 



This creature constructs a dwelling of comminuted shell exclusively, 

 in preference to all other materials, and is enabled, by the strength of the 

 tentacula, to avail itself of large fragments. In the natural state, it 

 generally takes shelter within some capacious empty shell, such as a valve 

 of the Venus islandica, there to establish its edifice ; and it likewise often 

 winds the tube over the surface. But many other situations are taken, 

 sometimes those very inaccessible, such as amidst groups of the Tubularia 

 indivisa, whence its artificial casement is inextricable. On all occasions 

 this tube is formed of irregular and unequal fragments, and lined with 

 the silky matter from an exudation of the animal. 



The Terebella may be induced to exercise its architectural faculties 

 by diminishing the light during day, as if night were approaching. If 

 supplied with different coloured fragments of shell, a variegated tube in 

 bands, or otherwise constructed, may be obtained. A beautiful edifice 

 is constructed of the shivered pearly interior strata of oyster shells. Thin 

 fragments are preferred to thick, but there is no evident discrimination 

 of suitable dimensions, as in the course of the work portions very large 

 are united to those very small. If the Terebella be restricted to the more 

 transparent fragments, a better view of itself within is afforded. 



A .specimen having been dislodged from its tube, and committed to 

 a vessel containing a few shelly fragments, some sand, and a number of 

 small Venetian beads, it employed the whole indiscriminately in fabri- 

 cating a new dwelling. But another, supplied with a quantity of sand, 

 together with a number of the same kind of beads, rejected the latter, 

 confining itself to the sand alone in constructing its edifice. It was not 

 a vigorous specimen. 



In default of comminuted shell, the Terebella conchilega will build a 

 tube exclusively of sand. 



By eliciting the propensities of this animal, the observer may have 

 much agreeable and interesting entertainment. 



If dislodged from its dwelling in a vessel of pure water, the Tere- 

 bella profits by the earliest provision of fresh materials to construct ano- 

 ther. While this is conducted up the side of a vessel, the tentacula, 

 those essential mechanical auxiliaries, are busily employed. A silky ten- 



2c 



