GENUS SPONGASTERISCUS. 229 



Spongocyclia charybdaea, 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. scyllaa. 



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 

 tetraceras. 



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 direcdy allied through the small group of the 

 Rhizo-Flagellata, previously described, with the Amceban 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 



