122 AQUA-TIC MICROSCOPY FOR BEGINNERS. 



is frequently found in company with Actinophrys," 

 among Lemna and other aquatic plants. It, too, 

 seems to like the sun. 



It feeds on other animals as well as on plants, tak- 

 ing larger victinis than the "sun animalcule" takes. 

 The Rotifers (Chapter VIII.) seem its favorite food. 

 A free-swimming animalcule or a Rotifer coming in 

 contact with the long rays often seems, as with Actin- 

 ophrys, to become incapable of escape; it is then 

 slowly drawn into the body and digested. 



6. DiFFLfJGiA (Figs. 97, 98). 



Shell brown; pear-shaped, ovoid or nearly spherical, 

 and formed of angular sand grains firmly cemented to- 

 gether. The upper part, the summit or fundus, may 

 be rounded and roughened only by the projecting edges 

 of the sand-grains, or rounded and bearing several 

 pointed spines likewise formed of sand. The lower 

 region may be prolonged as a short neck, at the end 

 of which is the rounded mouth for the passage of the 

 pseudopodia; or the shell may be without a region re- 

 sembling a neck. 



The animal which builds this protective case lives 

 inside of it, and is a little mass of colorless, or some- 

 times greenish, protoplasrn, somewhat- closely resem- 

 bling an Amoeba, and usually almost entirely filling the 

 cavity of the shell. The mouth of this domicile of 

 sand is circular, • and may be either smooth or with 

 several rounded teeth or lobes on its inner edge.' 



No part of the healthy and cowfortable animal, ex- 

 cept the pseudopodia, in aiiy of the shell-bearing forms, 

 ever passes through this mouth/ Wheii the shell is 

 made, the animal usually leaves it only when it is 



