CHALK MAKERS, OR FORAMINIFERA. 49 



FIG. 8. ENALLOSTEGA. 



the contents of the dredge, that the heavy dredge 

 frame had gone down with a plunge, and partly 

 buried itself in the soft, yielding bottom. The thr.oat 

 of the dredge thus be- 

 came partly choked, and 

 the free entrance of the 

 organisms on the sea 

 floor had been thus pre- 

 vented. The matter 

 contained in the dredge 

 consisted mainly of a 



compact " mortar," of a bluish colour, passing into a 

 thin evidently superficial layer, much softer and 

 more creamy in consistence, and of a yellowish 

 colour. Under the 

 microscope the sur- 

 face layer was found 

 to consist chiefly of 

 entire shells of Fo- 

 raminifera (Globige- 

 rina bulloidcs), large 

 and small, and frag- 

 ments of such shells mixed with a quantity of amor- 

 phous calcareous matter in fine particles, a little fine 

 sand.and many spicules, portions of spicules, and shells 

 of Radiolaria, a few spicules of sponges, and a few 

 frustules of diatoms. Below the surface-layer the 

 sediment becomes gradually more compact, and a 



E 



9. STICHOSTEGA. 



