42 GENERAL ORGANIZATION OF THE PROTOZOA 



Order 17. Cyrtoida. Haeckel recognizes twelve families. Skeleton similar to 



the preceding, but minus lobes or furrows. 

 Typical genus: Theoconus, Haeckel, 1887. 

 Legion 4. Cannopylea (Pheodaria). The chitinous central capsule is double, with 



a spout-like main opening at one pole and frequently with one or more 



accessory openings at the opposite pole. The skeleton is silicious and the 



spicules or bars are often hollow. The extracapsular protoplasm contains 



an accumulation of dark pigment granules (pheodium). 

 Order 18. Pheocystina. Haeckel recognizes three families. The skeleton con- 

 sists of distinct spicules or is absent altogether; the central capsule is in the 



centre of the spherical body. 

 Typical genus: Aulactinium, Haeckel, 1887. 

 Order 19. Pheospheria. Haeckel recognizes four families. The skeleton is a 



simple or double latticed sphere, and the central capsule is in the geometrical 



centre. 

 Typical genus: Oroscena, Haeck., 1887. 

 Order 20. Pheogromia. Haeckel recognizes five families. The skeleton is a 



simple latticed shell with a large opening at one pole; the central capsule is 



excentric, lying in the aboral half of the cell. 

 Typical genera: Pharyngella, Haeckel, 1887; Tuscarora, Murray, 1876; Haeck- 



eliana, Murray, 1879. 

 Order 21. Pheoconchia. Haeckel recognizes three families. The skeleton 



consists of two valves opening in the same plane as the three openings of the 



central capsule. 

 Typical genus: Concharium, Haeck., 1879. 



Flagella and Classification of the Mastigophora. — Flagella do 

 not present as many striking variations in form as do pseiidopodia. 

 Nevertheless, several different types exist. The simplest form assumed 

 is a slight, tapering filament broadest at the base and ending in an 

 invisibly fine tip. It moves constantly, the tip forming a circle, while 

 undulations or waves pass from base to extremity. In other types of 

 flagella the tip alone moves, while the base is a conspicuous filament 

 without undulation, the whole flagellum resembling a whip stock with 

 lash. It is a remarkable sight to see a peranema, for example, with 

 its stiff whip base, dragged along by the propelling movement of the 

 tip end of the slender lash. 



In some forms of mastigophora the flagellum appears to be flattened 

 out until it is quite band form. This is the case in some species of 

 peridinium, w4iere the bajid is drawn out to a pointed end, or in other 

 cases it retains the same width throughout. 



In many of the flagellates there is but one flagellum attached at one 

 end of the cell as in peranema or euglena. In other cases there are 

 two, and these may be of similar or dissimilar length. In bodo and 

 in most of the colony forming flagellates like dinobryon, synura, 

 uroglena, etc., one is much shorter than the other. In many forms of 

 bodo the longer flagellum trails along on the substratum so that the 

 cell has the appearance of sliding along on a runner (Fig. 15). In 

 some forms, especially the parasitic flagellates, this sliding flagellum 

 has apparently fused with the cell membrane, projecting o' /ard from 



