PROTOZOA. 3 



ing a distinct mouth. The principal forms included in this sec- 

 tion are the Flagellate Infusoria and the Sponges. 



SECTION C, EUSTOMATA. Ingestive area taking the form of a distinct 

 mouth. This section comprises only the Ciliated Infusoria. 



SECTION D, POLYSTOMATA. Ingestive areas distinct and multiple. 

 This section contains only the Suctorial Infusoria. 



CLASS I. GREGARINIDA. 



ORDER I. MONOCYSTIDEA. Monocystis (fig. 1, B). 

 ORDER II. EUGREGARINIDA. Gregarina (fig. 1, A and c). 

 ORDER III. ACANTHOPHORA. Stylorhynchus. 

 ORDER IV. DIDYMOPHYIDA. Didymopliyes (perhaps founded 

 upon conjugated forms). 



(Kolliker, Beitrage zur Kenntniss niedere Thiere (die Gattung Gregarina), 

 Zeitschr. fur Wiss. Zool., 1849 ; Stein, Untersuchungen uber die Gregari- 

 nen, Archiv fur Anat. und Physiol., 1848, and Zeitschr. fur Wiss. Zool., 

 1851 ; Schneider, Gregarines des Invertebres, Arch. Zool. Exper., 1873 

 and 1875 ; Biitschli, Kleine Beitrage zur Kenntniss der Gregarinen, Zeitschr. 

 fiir Wiss. Zool., 1881.) 



Fig. 1. Gregarinida. A, Gregarina gigantea, parasitic in the Lobster, enlarged, after Van 

 Beneden. B, Monocystis magna, parasitic in the Earthworm, enlarged, c, An immature 

 individual of Gregarina Uattarum, greatly enlarged, after Biitsehli, showing the separation 

 of the body into an anterior, middle, and posterior portion : n, Nucleus. 



