MICROSCOPE AT THE SEA-SIDE. 5 1 



Tethea (Fig. 142, PI. 5). Sometimes the spicula 

 assume a stellate form, and are even branched 

 (Fig. 143, PL 5). 



Amongst the lowest forms of animal life, none 

 are more interesting to the microscopic observer 

 than those belonging to the family of Foramini- 

 fera. They are thus called on account of the 

 minute holes which cover their shells. If we 

 suppose a creature as simple in structure as the 

 ama3ba or sun animalcule (Figs. 16 and 17, PL 1), 

 with the power of forming a little calcareous shell, 

 we should have a foraminifer. Some of these shells 

 have the form of a nautilus, and when first observed 

 they were supposed to belong to this group of shell- 

 fishes. In form they certainly resemble the higher 

 focus of mollusca (Figs. 20 and 22, PL 1). Some- 

 times, however, they are elongated or cone-shaped 

 (Fig. 21, PL 1). They may often be found alive at 

 the sea-side, nestling in the roots of the gigantic 

 laminarias which are so often thrown on the shore 

 after a storm. If the roots of these plants are washed, 

 and the deposit examined carefully, the foraminifera 

 may often be found alive. When this is the case, 

 they will be found to have the power of protruding 

 through the little holes in their shells their soft 

 bodies, in the form of long tentacles (Fig. 23, PL 1). 

 With these they seern to have the power of moving 

 as well as of taking up the matters by which they 

 are nourished. The shells of these creatures are 

 not so small but they may be seen with the naked 

 eye, and they need only a low power to observe all 

 their structure. They are found at great depths in 

 the ocean, and have been brought up by the dredge 

 from the deepest parts of the Atlantic. They are 

 very abundant in some rocks, especially in the 

 chalk : they may be obtained from the latter 

 substance by rubbing a piece of chalk with a brush 

 E 2 



