356 THE NATURAL HISTORY REVIEW. 



which he illustrates in a tabular form on p. 423 (Vol. II.) It must 

 be confessed that this view of the matter is not a very satisfactory 

 one. Professor Bronn's parallel series are exceedingly fanciful, and 

 they certainly furnish no evidence in favour of the retention of the 

 Echinodermata in the same primary group with the Coelenterata. In 

 the classification of the latter, moreover, there is much that seems to 

 us unsatisfactory, there is no recognition of the division of the 

 group into the two sections of Hydrozoa and Actinozoa, which 

 appears to be fully warranted by the well marked differences of 

 organisation presented by these animals, and the four classes into 

 which the Coelenterata are divided are of very unequal value. On the 

 lowest step of the classificational ladder we find the JPolypi (=An- 

 thozoa) which we should have thought better placed at the highest 

 point ; these are followed by a class of HydrcB, including only the 

 fresh-water Polyps of the genus Hydra ; whilst the third class, under 

 the name of MeduscB, embraces within its wide boundaries, the whole 

 of the Hydroid Polypes, Medusw and SijphonophorcB. The fourth 

 class again includes only the Ctenophora. 



Of the classification of the Echinodermata we need say but 

 little. Professor Bronn has simply elevated the five orders of these 

 animals usually recognized by naturalists to the rank of classes, under 

 the names of Blastoidea^ Crinoidea, Asterioid, JEcMnoidea and 

 Scytodermata(=IIolothurioidea.) In taking this course, Professor 

 Bronn has realised a notion which, we think, must have frequently 

 occurred to Naturalists, namely that the difi'erences between the 

 various groups of Echinodermata, are of more than ordinal value ; in 

 fact the characters on which these groups are founded are fully equal 

 in importance to those by which the classes of Arthropoda are dis- 

 tinguished. Our only surprise is, that having gone so far he did not 

 advance a step further by forming the Echinodermata into a sixth 

 primary group, a proceeding which, notwithstanding the annuloid 

 relationships of these animals, would certainly have been preferable 

 to leaving them in the same sub-kingdom with the Coelenterata. 



The third volume on the Malacozoa, which is still incomplete, 

 although it already extends to nearly 1300 pages, is only partly the 

 work of Professor Bronn, who had advanced in his ascending classi- 

 fication as far as the Nudibranchs at the time of his lamented 

 decease. This portion of the book has been continued, as already 

 stated, by Dr. Keferstein of Gottingen. 



The classification of the Mollusca has been so fully elaborated by 



