428 THE DEPTHS OF THE SEA. [chap. vii. 



pear-shaped things, a centimetre long, with a single 

 osculum at the top, and the whisp like a small 

 brush. At this stage the Palythoa is usually absent, 

 but when the body of the sponge has attained 15 mm. 

 or so in length very generally a little pink tubercle 

 may be detected at the point of junction between 

 the sponge body and the coil, the germ of the first 

 polyp. 



Hyalonema lusitanicum, Barboza du Bocage, the 

 species met with in the British seas and along 

 the coast of western Europe, appears to be local, 

 but very abundant at the stations where it occurs. 

 I am still in doubt whether we are to regard it 

 as identical with the Japanese species, H. sieboldi, 

 Gray. 



During Mr. Gwyn Jeffreys' cruise in 1870, two 

 specimens of a wonderful sponge belonging also to the 

 Hexactinellidse were dredged in 374 fathoms in rocky 

 ground off Cape St. Vincent. Tbe larger of these 

 forms a complete vase oi a very elegant form, nearly 

 ninety centimetres in diameter at the top and about 

 sixty in height (Fig. 67). The sponge came up folded 

 together, and had much the appearance of a piece 

 of coarse, greyish-coloured blanket. Its minute 

 structure is, however, very beautiful. It consists, 

 like Iloltenia, of two netted layers, an outer and 

 an inner, formed by the symmetrical interlacing of 

 the four cross branches of five-rayed spicules ; and, 

 as in Jloltenia and Rossclla, the sarcode is full of 

 extremely minute five and six-rayed spicules, which, 

 however, have a thoroughly distinct character of 

 their own, with here and there a very beautiful 

 rosette-like spicule, another singular modification of 



