1869.] and Membranipora Bengalensis. 29 



this change would not be so easily perceptible, as when the organs are 

 numerous, various and more highly developed. Expressing, there- 

 fore, this idea in a more general way, we imply that, within certain 

 limits,* forms of lower organisation possess a greater faculty of ac- 

 commodating themselves to different conditions of life, than more 

 highly organized beings. 



In the present communication I shall record a very interesting case 

 of the persistency of a form under different conditions, relating to a 

 coralline species, a so-called sea-anemone, and to another species 

 belonging to the Bryozoa, or the lowest organized Molluscs. With 

 respect to the anatomy and physiology of these two species, I shall state 

 all the data which I have obtained, for though some of them are not 

 directly new discoveries, still detailed records of these animals are so 

 rare, that I must treat the subject somewhat at length, in order to 

 be intelligible ; and this, I think, is very necessary as naturalists have 

 become in late years rather sceptical regarding new species, only 

 characterised by few high sounding, — occasionally unintelligible, — 

 terms. Besides this, it would be impossible for me to give additional 

 observations, without bringing them into a systematic connection with 

 those which are already known on this subject. 



Phylum, CcELENTERATA.f 



(Cnidozoa or Actinozoa.) 

 The name Cnidozoa is derived from the word at kvlSoli, used by 

 Aristotles for the designation of this group of animals ; the same 

 word is now retained for the name of special, defensive cells which 

 characterize these animals, as will be shown subsequently. For the 

 extent of the various divisions of the Cgelenterata, Leukart and 

 Kolliker's works have to be consulted. 



* It is very often stated that the more highly organized forms possess a greater 

 faculty of accommodation ; this is, however, I think, a mistaken idea, Originat- 

 ing partly in the comparison of the same external influences upon organisms 

 of different kind and decree, partly in the difficulty of noticing any changes in 

 the lower organisms. The comparison must always be a truly relative one ; for 

 in differently organized forms, there is a different amount of forces present to 

 counteract the influence of external agencies. 



t The first few principal divisions are noticed according to Haeckel's Generate 

 Morjphologie, 1866, vol- II, p. L. 



