PROTOZOA. 9 



(Saville Kent, Manual of the Infusoria, 1880-81 ; Stein, Der Organ- 

 ismus der Infusionsthiere, 1859-67 ; Claparede et Lachmann, fitudes sur 

 les Infusoires et les Ehizopodes, 1858-61 ; Allman, Recent Progress in our 

 Knowledge of the Infusoria, Journ. Linn. Soc., 1875 ; Ehrenberg, Die In- 

 fusionsthierchen als volkommene Organismen, 1838.) 



Fig. 6. Ciliated and Flagellate Infusoria. A, Bursaria truncatella, enlarged 50 times. B, 

 Nyctotherus cordiformis, enlarged 150 times, c, Amphileptus anser, enlarged 120 times. D, 

 Ceratium tripos, enlarged 250 times, with its carapace and single flagellum. E, Monosiga 

 angustata, enlarged 2500 times : n. Nucleus ; c, Contractile vesicle ; /, Flagellum ; m, Mem- 

 branous collar surrounding the base of the flagellum. (After, or copied from, Saville Kent.) 



CLASS IV. PORIFERA (SPONGIDA). 



ORDER I. MYXOSPONGLE. 



Sub-ord. Halisarcidse. Halisarca. 



ORDER II. CERATOSA (Ceratospongise). 



Sub-ord. 1. Gumminida. Chondrilla, Corticium, Osculina. 



Sub-ord. 2. Ceratina. Luffaria, Aplysina. 



Sub-ord. 3. Psammonemata. Euspongia, Dysidea, 



Sub-ord. 4. Khaphidonemata. Chalina. 



