748 



APPENDIX. 



has the anterior-and-posterior, or cephalic and anti-cephalic, polarity, connected 

 with a well-developed nervous system. The Radiates among animals are allied 

 in this respect to plants, being Animal representatives of the Vegetable radiate 

 type ; and this is the ground of the subdivision of the Animal kingdom stated 

 on page 596 (§ c). Among the Radiates, the Polyps (the lowest of the three 

 classes), in their modern and more typical kinds (see Appendix F), have a six- 

 rayed structure, the Acalephs a four-rayed, the Echinoderms (or highest) a 

 five-rayed ; and these last look forward through their many unsymmetrical forms 

 towards the eephalic polarity of the other sub-kingdoms. 



2. Protozoans. — The two most common, and geologically the most important, 

 subdivisions of the Protozoans, are mentioned on page 163. A few remarks on 

 the classification of the group are added. 



The Protozoans include those minute animal species in which neither of the 

 four grand systems of the Animal kingdom (the Radiate, Molluscan, Articulate, 

 and Vertebrate) is distinctly brought out. They represent life simply, or sys- 

 temless. Their analogues among plants are the Algse, which are also systemless ; 

 that is, are without the radiate structure typical of the Vegetable kingdom. 

 Protophytes are only microscopic Algae. 



Although the grand systems in Zoology are unpronounced, there are still faint 

 indications of them generally observable, or to be inferred from resemblances to 

 the embryonic condition of higher species, and these are the most fundamental 

 distinctions for their arrangement. The groups accordingly appear to be the 

 following : — 



1. Actinozo'oids ; or, Radiate Protozoans, as the Sponges, Polycystines, Noc- 

 tilucae, etc. The mineral secretions, when any exist, are, with few exceptions, 

 siliceous. (A few sponges have calcareous spicula.) 



A few species are here figured. Fig. 976 represents a Spherozoum (S. orien- 

 tale D.), a gelatine-like spheroidal mass, containing many minute circular spots, 

 each set about with siliceous spicula (see Amer. Jour. Sci. [2] xxxv.). Fig. 979 a 

 is the mass, natural size, and b one of the circular spots or individuals of the 



Fig. 979. 



Figs. 980-982. 



Protozoans. — Pig. 979 a, Spherozoum orientale, natural size ; b, one of the individuals in 

 the compound mass enlarged ; 980, Lychnocanium Lucerna (X 100) ; 981, Eucyrtidium 

 Mongolfieri (X 100); 982, Halicalyptra fimbriata (X 75). 



compound mass, enlarged. This species was obtained by the author in the Pacific 

 in lat. 28° to 30° N., long. 178° W., where they were so abundant as to make 

 the water look cloudy. The Spherozoa are supposed to be closely related to 



