I900.] Sponges, C orals ^ and Jellyfish. 259 



The question whether sponges are animals or plants has long ago been 

 settled in favour of the former view. Their protozoan nature has been 

 upheld by many zoologists, though the opinion that they belong to the 

 Metazoa is now generally adopted among zoologists. It is, however, 

 when we come to a further definition of their position in the system that 

 modern authors are so much divided. Are sponges to be regarded as an 

 independent phylum distinct from all the rest of the animals, or should 

 they be placed in one of the existing sub-kingdoms ? Since the coelen- 

 terate theory, according to Prof. Minchin, has become quite untenable, 

 he rightly adopts the view so ably advocated b}' Sollas and Biitschli that 

 sponges belong to a separate phylum, which probably originated from a 

 choanoflagellate infusorian ancestor. It is to be regretted therefore that 

 Mr. Bourne, in the sixth chapter (p. 4) again classes the Porifera among 

 the Coelentera. 



The chapter on Enterocoela and Coelomocoela by Prof. Ray Lankester 

 is particularly interesting. The term ccelom was originally applied to 

 the body cavity in vertebrate animals. The same term is now extended 

 to the cavity or organ in other groups of animals which may be consi- 

 dered genetically identical with this primitive vertebrate pleuro- 

 peritoneal cavity. As Prof. Lankester remarks, the presence of the 

 ccelom is of the highest physiological importance. Hence all the 

 Metazoa, except sponges, are divided into those in which the sole cavity 

 is the enteron — the Enteroccela— and those in which the ccelom is pre- 

 sent as an independent second cavity — the Coelomocoela. The author 

 then enumerates the phyla included in these two grades, their chief 

 organs and organ-systems and discusses the various theories connected 

 with the ccelom in a strikingly novel and attractive manner. 



The chapter on the Hydromedusse and the Scyphomedusae, which 

 contain the jelly-fishes and their allies, has been very ably written by Dr. 

 Fowler. The illustrations, many of them new, are throughout the book 

 excellent, though some of the diagrams might with advantage have 

 been printed in different tints, as has been done by Delage and 

 Herouard in their great French work on zoology. 



Finally, Mr. Bourne deals with the Anthozoa and the Ctenophora. The 

 apparently aberrant group containing Ctenoplana and Cceloplana which was 

 supposed to connect the ctenopho^es with the planarian worms, are now 

 classed among the former under the order Platyctenae. Until the 

 development of these peculiar forms have been studied, they give us no 

 further clue as to the suggested relationship of Platyhelminthes and 

 Ctenophora. 



The volume (Part II.) now before us quite sustains the high standard 

 of excellence which characterizes its predecessor, and justifies in every 

 sense the opinion already expressed in this Journal. 



R. F. S. 



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