HYDRA TUBA. 69 



is protruded in the shape of a four-sided tube, the 

 orifice of which the creature keeps continually moving 

 from side to side, as though in search of nourish- 

 ment ; but on touching the little animal, this mouth, 

 or proboscis as we might almost call it, is at once 

 retracted ; the oral aperture, moreover, is capable of 

 enormous dilatation, opening when the animal is about 

 to swallow food, until it equals the capacity of the 

 stomach itself. 



The shape of the Hydra tuba, as represented in the 

 figure referred to, resembles a hollow cone scarcely 

 five lines in length, attached by its apex to some fo- 

 reign body, with thirty or more very extensile, flexible, 

 slender tentacula descending from the opposite mar- 

 gin collectively, forming a beautiful silk-like pencil 

 waving amidst the water. The natural colour of the 

 animal is universally dingy- white, or sometimes faintly 

 orange, perhaps according to the season, or the quality 

 of the food upon which it lives. 



The tentacles, which exactly resemble so many fila- 

 ments of spun glass, are, when fully extended, con- 

 siderably longer than the body of the animal, and are 

 moveable in all directions ; they are likewise exceed- 

 ingly sensitive, and, if rudely touched, at once join 

 together into a bundle and shrink up into a very 

 small compass ; but they are never entirely retracted 

 into the interior of the body. 



The body of the Hydra tuba is a simple gelatinous 

 bag, so irritable and contractile, that, when alarmed, 

 the creature shrinks to half its original size ; and yet 

 at the same time so dilatable, that the animal swallows 

 prey apparently much larger than itself. Its move- 



