GENUS SPONGASTERISCUS. 229 



Spongocyclia charybdsea, Hkl. PL. I. FIG. 25. 



General contour of test escutcheon-shaped, flattened and angular ante- 

 riorly, slightly widest centrally, tapering and obtusely pointed at the 

 posterior extremity ; central capsule composed of from seven to fourteen 

 concentric chamber-cycles, its diameter equalling one-half of the entire 

 test ; flagellum stout, exceeding the length of the test, projecting from the 

 centre of the anterior border. Length 1-72". 



HAB. Pelagic: Messina. 



Additional species, figured and described by Haeckel, are distinguished by the 

 respective titles of Spongocyclia cycloides, S. elliptica, S. orthogona, and S. scyllcea. 



GENUS III. SPONGASTERISCUS, Haeckel. 



Test siliceous, consisting of a central discoidal capsule composed of 

 concentric and symmetrical chamber-cycles, surrounded by an irregular 

 trabeculate siliceous lattice-work, as in Spongocyclia, but which, in place of 

 being simply subcircular or escutcheon-shaped, is developed into distinct 

 angular arm-like processes, which lie in the same plane as the flattened 

 central disc. 



Spongasteriscus quadricornis, Hkl. 



Central capsule circular, flattened, composed of from eight to sixteen 

 concentric chamber-cycles, radiating arm-like processes four in number, 

 subequal, triangular, forming two basally united pairs at the anterior and 

 posterior regions, their length equal to one-third of the diameter of the 

 central disc ; flagellum projecting from the notch between the anterior pair 

 of angular processes. Diameter of central disc 1-96". 



HAB. Pelagic : Messina. 



One additional species is described by Haeckel under the title of Spongasteriscus 

 tctraceras. 



Order IV. FLAGELLATA-PANTOSTOMATA, S. K. 



Animalcules simply flagelliferous, having in their characteristic adult 

 state no supplementary lobate or ray-like pseudopodic appendages ; oral 

 or ingestive area entirely undefined, food-substances being incepted in- 

 differently at all points of the periphery. 



Among the typical Infusoria-Flagellata, this order may be said to represent the 

 lowest and least specialized, it being directly allied through the small group of the 

 Rhizo-Flagellata, previously described, with the Amoeban order of the Rhizopoda. 

 Many of the generic and specific forms at present referred to this section must be 

 regarded as occupying therein a purely provisional position, it not being improbable 

 that the animalcules, upon further acquaintance, may be found to possess a distinct 

 oral aperture, and thus demand transfer to the succeeding order of the Flagellata- 

 Eustomata. While again, in a very considerable number of instances, the ingestion 

 of food-substances at all points of the periphery has been directly observed, it would 

 seem highly probable that where neither this phenomenon nor the presence of an 



