CLASSIFICATION OF THE MASTIGOPHORA 



49 



Order 1. Adinida. Dinoflagellates without furrows, the two flagella free in the 



water, the transverse with movement the same as though the furrow were 



present. 

 Typical genera: Prorocentrum, Ehr., 1833; Exuviella, Cienk., 1882. 

 Order 2. Diniferida. Dinoflagellates with furrows, one transverse, the other 



longitudinal. 

 Family 1. Peridinidce. The transverse furrow is without wide ledges and the 



shell may be absent. 

 Typical genera: Peridinium, Ehr., 1832; Ceratium, Schrank, 1793; Gleno- 



dinium, Ehr., 1835; Gymnodinium, Stein, 1S78. 

 Family 2. Dinophysidw. The borders of the cross furrow are developed into 



great ledges, making a deep furrow for the flagellum. 

 Typical genera: Dinophysis, Ehr., 1839; Cithiristes, Stein, 1883; Amphidinium, 



Clap, and Lach., 1859; Ceratocorys, Stein, 1883; Triposolenia, Kofoid, 190G. 

 Order 3. Polit)IXIDA. The order consists of but one genus, Polykrikos, Biitschli, 



1873, which is characterized by a naked body, by several transverse furrows 



and flagella, by macro- and raicronuclei, and nematocysts. 

 Subclass 3. Cystoflagellata. ^larine protozoa, which are plant-like in having a 



highly parenchymatous body, a single nucleus and a firm membrane. The 



young forms pass through a dinoflagellate stage in development. 

 Three genera: Noctiluca, Suriray, 1836; Leptodiscus, Hertwig, 1877; Craspe- 



dotella, Kofoid, 1905. 



Cilia, and Classification of the Infusoria.— Cilia are quite differ- 

 ent from flagella, being shorter and moving with a sharp stroke in 

 one direction and with a slower, non-forceful recovery in the opposite 

 direction. Like the flagelliun, the cilium is thicker at the base and 

 tapers to a fine point, while it owes its contractility to the presence of a 



Fig. 17 



Aspidisca hexeris, Quen. 



An hypotrichous ciliate with brushes of fused cilia. 

 (After Calkins.) 



fihiment of kinetic granules placed along one edge of the ciHuni, the 

 contraction of this thread furnishing the power of the cilium, while 

 the synchronous contraction of thousand-; of similar cilia furnishes 

 the motive power of the organism. 



In some forms, as in diUptus or paramecium, and the majority of 



