P0LTPE3. 



59 



bling horn, an exudation from the gelatinous integument; 

 and this tube, at every bud, takes the form of an open 

 cell or cup (varying much in shape according to the 

 species), into the cavity of which each individual polype- 

 head can withdraw itself on alarm, and from the orifice of 

 which it protrudes and expands when seeking prey. 



In the accompanying Plate, the figure a represents one 

 of the most regular of these species ; and, therefore, one 

 whose construction is peculiarly intelligible. It is a 

 group of the Polyps named Laomedea geniculata, very com- 

 monly found springing from the broad leathery leaves of 

 the fingered tangle, Laminavia digitata, that great olive- 

 brown sea-weed that waves its hugs fronds to and fro just 

 below the level of the lowest spring-tides. The first ap- 

 pearance of the Polype is a slender horny thread that 

 creeps along the surface of the leaf, adhering firmly to its 

 surface. Presently such a tiny budding stem as we have 

 just described springs up from the root-thread, which con- 

 tinues to creep on its way over the leaf, now and then 

 bending its course at an abrupt angle, and sending up 

 fresh stalks at regular intervals, which at length become a 

 miniature forest. A few such stalks are represented at a, of 

 the natural size ; and, at fig. b, one of these, or at least a 

 portion of one, is shewn as it appears considerably mag- 

 nified. The horny tube is seen, with its cup-like cells: 

 the body of the Polype, a thread of gelatinous flesh, per- 

 meates the stem and the branches, maintaining a common 

 life : at intervals, the polype-heads project in the manner 

 of buds, each occupying its transparent cell, and displaying 

 its crown of tentacles which radiate on every side. The 

 lower cells are commonly empty, the polype-heads having 



