CHAP. IL] FROM PORTSMOUTH TO TENERIFFE. 135 
Lymani and of an undescribed species of the same genus. The 
trawl seems specially suitable to the capture of Holothurids; 
indeed, without its use we should never have imagined that ani- 
mals of this group occurred so abundantly as they do, and ac- 
quired so considerable a size in deep water. Almost every 
haul along the coasts of Portugal and Africa yielded several 
species, and particularly many specimens of a remarkable form, 
referred to a section of the order with which we are now very 
familiar as inhabitants of the deeper regions of the sea. The 
animal is of a rich violet color. Like Psolus, it has a distinct 
ambulatory surface with a central double row of water -feet. 
The body-cavity is small, but the perisom is represented by an 
enormously thick layer of jelly, which rises on either side of 
the middle-line of the back into a series of rounded lobes, each 
perforated for the passage of an ambulacral tube, and corre- 
sponding, therefore, to an ambulacral foot. The upper pair of 
vessels of the trivium send out series of leaf-like sacs loaded 
with purple pigment, which fringe the ambulatory disk on ei- 
ther side, and appear to be chiefly concerned in the function of 
respiration. 
This haul gave us another interesting evidence of the wide 
geographical distribution of some of the characteristic forms of 
the deep-sea fauna. Several examples of a species of the genus 
Euplectella were entangled in the netting of the trawl. 
In the year 1841, Professor Owen gave an excellent descrip- 
tion, in the Transactions of the Zoological Society of London, of 
a wonderfully beautiful sponge which had been lately received 
from the Philippine Islands, and which he named /plectella 
aspergilum (Fig. 28). In the specimen described by Owen, 
the soft gelatinous coating had been entirely removed, and noth- 
ing remained except the skeleton, composed of silica, and resem- 
bling an exquisitely delicate fabric woven in spun glass. The 
skeleton is in the form of a slightly curved tube, contracted 
downward and expanding upward to a wide circular mouth 
