284 GASTEEOPODA. 



purpose of extracting the colouring fluid, especially as 

 Pliny describes this as being the mode in which the 

 dye was obtained. The shells, when examined, 

 proved to be those of Murex truncujus, still found 

 abundantly on the neighbouring beach. 



The Stromb-shells (Stromhus) have the siphonal 

 canal straight, or inflected towards the right side. 

 The external border of the opening of these shells 

 expands with age, and sometimes spreads out into 



' V'!' 



Fig. 223.— pelican's foot strombus. 



long, finger-like prolongations, so that, when they 

 arrive at maturity, their form is very different* from 

 that of the young. Some species belonging to 

 this carnivorous genus are also remarkable for their 

 great size, as, for example, the common Conch-shell 

 {Stromhus gigas) of the West Indies, valued as a 

 chimneypiece ornament on account of its striking 

 appearance, and the beautiful rosy hue of its interior. 



Order Tubulibeanchiata.* 



In this order of Gasteropods the shell takes the 

 form of a tube, more or less irregular in its sha23e, 

 but always presenting a spiral contom' near its com- 

 mencement. These tubes very much resemble 

 those of certain Annelidans (Serjml^), with which 

 they Avere long confounded. They are generally 

 found entwined together, and mixed up with coral 

 beds. As the included animals are thus fixed, 



* Tubulus, a tube; branchiae, gills — tuhe-gilled. 



