8 FORAMINIFERA 



plain how such tests are made of one sort of building material, 

 spicules, mica-flakes, ambulacral plates of brittle stars, etc. The 

 occurrence of specimens of Iridia on the leaves of Posidonia 

 some inches above the sea bottom, while its test is composed of 

 material from the bottom, is also explained. The material could 

 easily be carried up to this elevation while ingested in the mov- 

 ing mass of protoplasm, and then concentrated on the surface 

 when the animal settled down to form its test. 



Food 



In general, so far as known, the usual food of the foraminif era 

 consists of vegetable material, the diatoms and various other 

 algae furnishing the greater part. In some of the pelagic forms 

 it has been observed that copepods are captured and eaten as 

 well as other protozoa. 



Color 



Living specimens often are beautifully colored. From my own 

 observations, it would seem that the protoplasm itself is differ- 

 ently colored in different groups. The Miliolidae often have a 

 light pinkish color, while the Orbitolitidae are usually of a 

 salmon color. Other groups have the protoplasm various shades 

 of brown and in some it is wholly or in part colorless. This mat- 

 ter of color may be of greater significance than now appears if 

 it is studied in connection with the relationships of the different 

 groups. 



The test itself is often colored, especially when fresh. The 

 Homotremidae are brilliantly colored, pink, red or orange. 

 Some of the Calcarinidae also show marked color when fresh. 

 Rotalia rubra, a common species of the West Indian region, is a 

 deep red or pink as is also Glohig erinoides rubra. Many of the 

 Rotaliidae have a brownish color especially in the young. Near- 

 ly all the arenaceous forms are reddish- or yellowish-brown. 



