THE GLASS-SPONGES. 545 



purchase, like that of a screw. Venus's Flower-Basket has the small 

 end of the cornucopia plunged deeply into the sea-ooze, and from its 

 extreme end threads go out with an upward and outward curve. Thus 

 the mud rests upon them on the inside of the curves, and holds the 

 dish-shaped tuft of fibres down. Pheronema has its threads near the 

 extremities marked by projecting notches, while at the very extremity 

 it is actually anchor-shaped, as shown by a thread magnified (Fig. 8). 

 Holtenia has a great mop of fine roots, like what is often seen when 

 changing a plant from one flower-pot to another. Hossella has a great 

 outlay of mooring-threads, with frequently a line quadrate-barbed at 

 its extremity. This is well shown in Fig. 5. These lines have actually 

 at the bottom a four-hooked grapnel. 



A very interesting fact is this : The study of these Hexactinellidoe 

 has made clear as light the structure and character of the curious 

 flinty fossils obtained from the cretaceous formation, and known as 

 Ventriculites. Fig. 9 shows one of these fossils, and Fig. 10 shows 

 its beautiful spicular structure. It is now plain that they were glass- 

 sponges, and also belonged to the family Ilexaetinellidce / while the 

 deep-sea dredging, as it brings up these so-long-concealed witnesses, 

 is proving that our notion, that the cx-etacean forms of life belonged 

 wholly to the great past, needs careful revision ; for it may be that 

 this ante-biotic theory is not quite correct. 



Fio. 10. 



Outer Surface op the Fossil Sponge. Ventriculites Simplex, magnified fonr times, show- 

 ing the ventricles which make the outer ornament. (See Fig. 9.) 



And there are many strange and also beautiful forms of life that 

 are the companions of these deep-sea sponges. Yes, and even almost 

 formless conditions of life are there. A substance like albumen, a sort 

 of protoplasm, spreads over the broad acres of the sea-bottom. Per- 

 haps it is the manna which Providence has given to these wonderful 

 creatures that occupy these deserts beneath the sea. Certain it is that, 

 in two senses, the dredger is plunging into the profoundest physical 

 problems. How precious, then, is every grain of mud obtained from 

 vol. in. 35 



