AMPHITRITE. 247 



The animal sometimes reverses itself in its gelatinous dwelling, then 

 remaining a short time with the head downwards ; and sometimes it 

 forms an additional orifice above therein shewing an analogy to the 

 genus Terebella. 



It is surprising how such a diminutive creature can exhibit secre- 

 tion so abundant in a definite form. Perhaps the exudation is from the 

 whole body ; and it seems invariably concomitant on renewal of the sur- 

 rounding element. 



Buoyancy is promoted by many air bubbles, which are especially 

 about the orifice. If the tenant be vigorous, it is constantly there dis- 

 playing its plume ; if weak and languishing, it hangs far out of the tube, 

 like the preceding species. 



This is a timid animal ; it retreats suddenly for safety. Then, as 

 well as during its return, it performs a partial revolution, the branchiae, 

 meanwhile, being closed as a spiral, whereby the entire plume resembles 

 a screw of multiplied threads. Some weight may be thence allowed to 

 Viviani's characteristic Spirographus, as distinguishing the genus Am- 

 phitrite. 



This, the Floweret Amphitrite, seems rare in the Scotish Seas. Only 

 about six specimens have occurred to me, the last at the interval of 

 seventeen years from those preceding it. None survived above four 

 months. 



PLATE XXXI. 



FIG. 9. Amphitrite jioscula. 



4. MISCELLANEOUS. 



Besides the preceding species, whose features are sufficiently defined, 

 there are some other annulose animals which may be placed provision- 

 ally in the vicinity of the Amphitrite. Farther observation will point 

 out their precise position in the Systema if they ought to remain here. 



