50 MANUAL OP ZOOLOGY. 



, TABLE OF D ORBIGNY'S ARRANGEMENT OF THE FORAMINIFERA. 



Order 1. Monostega. Body consisting of a single segment; the shell of 

 a single chamber. 



Order 2. Stichostega. Segments arranged in a single row, in a straight 

 or slightly curved line. 



. Order 3. Hdicostega. Segments arranged in a spiral, the shell forming a 

 number of convolutions. (The ' nautiloid' Foraminifera.} 



Order 4. Entomostega. Segments arranged on two alternating axes 

 forming a spiral. 



Order 5. Enallostega. Segments arranged on two or three alternating 

 axes, not forming a spiral. 



Order 6. Agathistega. Chambers wound round an axis ; each segment 

 embracing half the entire circumference. 



TABLE OF SCHULTZE'S ARRANGEMENT OF THE FORAMINIFERA. 



Section 1. Helicoidea. Segments arranged in a convolute series. 

 Section 2. Ehabdoidea. Segments placed in a direct line. 

 Section 3. Soroidea. Segments disposed in an irregular manner. 



AFFINITIES OF FORAMINIFERA. The Foraminifera are related 

 on the one hand to the Amcebea and 011 the other to the 

 Spongida. From the former the 'unilocular ' Foraminifera differ 

 both in the possession of an external envelope, and in the 

 much less highly differentiated characters of their sarcode ; 

 but the points of resemblance are obvious, and in such forms 

 as Aciinoplirys and Lieberkulmia we are presented with an 

 apparent transition between the two orders. From the shelled 

 Amcebea, such as Arcella, the Foraminifera are broadly separated 

 by the absence in the former of pseudopodial pores, and are 

 fundamentally distinguished by the different nature of the 

 sarcode-body. 



To the Sponges the Foraminifera are related in various 

 ways, one of the most striking links being found in Carpen- 

 teria, a singular attached form of Fomminifer. The shell, 

 namely, of Carpenteria is conical and calcareous, composed of 

 an aggregation of chambers arranged in a spiral, and having 

 its walls perforated by numerous foramina of a minute size. 

 The interior of the chambers, however, is filled with ' a fleshy 

 sponge-like body,' strengthened by numerous spicula. 



BATHTBIUS, COCCOLITHS, AND COCCOSPHERES. It may be as 

 well to notice here a singular organism which is certainly 

 referable to the Rhizopoda, though its exact affinities are 

 doubtful. Certain minute oval or rounded bodies have loug 

 been known as occurring attached to the surface of the shells 

 of Foraminifera, and they were originally described by 

 Professor Huxley under the name of coccoliths. Subsequently 

 it was discovered by Dr. Wallich that these singular bodieM 

 occur not only in the free condition, but also attached to the 



