ON CLASSIFICATION. 



1st Division. ACRITA* (M'Leay); Cryptoneura, (Rudolphi)-f- 

 Protozoa,]. Oozoa. 



(8.) In animals belonging to this division, no nervous filaments or 

 masses have been discovered, and the neurine or nervous matter is 

 supposed to be diffused in a molecular condition through the body, 

 mixed up with the gelatinous parenchyma of which they consist. 

 Possessing no brain or central mass, to which external impressions 

 can be transmitted, or nervous filaments calculated to conduct 

 sensations to distant points of the system, or associate muscular 

 movements, they are necessarily incapable of possessing those 

 organs which are dependent upon such circumstances ; instruments 

 of the external senses are therefore totally wanting, or their ex- 

 istence at least is extremely doubtful ; the contractile molecules of 

 their bodies are not as yet aggregated into muscular fibre. The 

 alimentary apparatus consists of canals or cavities, permeating the 

 parenchyma of the body, but without distinct walls, as in the 

 higher divisions, where it floats in an abdominal cavity. The 

 vascular system, where at all perceptible, consists of reticulate 

 channels, in which the nutrient fluids move by a kind of cyclosis. 

 Their mode of reproduction is likewise conformable to the diffused 

 state of the nervous and muscular systems ; not only are most 

 of them susceptible of being multiplied by mechanical division, 

 but they generate by spontaneous fissure, as well as by gemmae, 

 ciliated gemmules, and true ova. Many appear to be made up of 

 a repetition of similar parts, forming compound animals of various 

 forms, and different degrees of complexity. In this division are 

 included 



1. Sponges. 



2. Polyps. 



3. Polygastric animalcules. 



4. Acalephse. 



5. Parenchymatous Entozoa or Sterelmintha. 



* Horae Entomologicae, Vol. I. Part II. page 202. We adopt the term, however, 

 according to its improved application by Mr. Owen, viz. to the exclusion of the higher 

 organized Polyps and Entozoa, and the admission of part of the Radiata of Macleay. 



t Beytriige sur Anthropologie. 1812. J U^uros, first ; 2*>ov, animal. 



'(lov, an egg ; 2&Jv, animal, so called by Carus, because they resemble the eggs or 

 rudiments of more perfect forms. 



