chap, ii.] THE CRUISE OF THE 'LIGHTNING.' 7;} 



and finally passes out by the large ' osculum ' at the 

 top. Over the upper third of the sponge a multitude 

 of radiating rigid silicious spicules form a kind of 

 ornamental frill, and from the lower third a perfect 

 maze of delicate glassy filaments, like fine white hair, 

 spread out in all directions, penetrating the semi-fluid 

 mud, and supporting the sponge in its precarious bed 

 by increasing its surface indefinitely while adding 

 but little to its weight. 



This is only one of the ways by which sponges 

 anchor themselves in the ooze of the deep sea, 

 Hyalonema sends right down through the soft 

 mud a coiled whisp of strong spicules, each as thick 

 as a knitting needle, which open out into a brush 

 as the bed gets firmer, and fix the sponge in its place 

 somewhat on the principle of a screw pile. A very 

 singular sponge from deep water off the Loffoten 

 Islands spreads into a thin circular cake, and adds 

 to its surface by sending out a flat border of silky 

 spicules, like a fringe of white floss- silk round a 

 little yellow mat ; and the lovely Euplectella, whose 

 beauty is imbedded up to its fretted lid in the grey 

 mud of the seas of the Philippines, is supported by 

 a frill of spicules standing up round it like Queen 

 Elizabeth's ruff. 



The sponges of the deep-water ooze are by no 

 means confined to one group. The Hexactinellidce 

 are perhaps the most abundant, but corticate sponges 

 even, closely allied to those which look so rigid when 

 fixed to stones in shallow water, send out long anchor- 

 ing spicules and balance themselves in the soft mud 

 (Fig. 7) ; and off the coast of Portugal Mr. Gwyn 

 Jeffreys dredged in 1870 several small forms of 



