I 



60 t REVIEWS. k 



what extent their fellow-labourers in these kingdoms have aided in the 

 onward progress of science. We must conclude, therefore, that M. Edwards 

 has some good and sufficient reason for not treating more at length of those 

 lower tribes ; and we can think of none so probable as an unwillingness to 

 make much change in a book of which so many copies are in circulation. 

 In all schools and colleges, inconvenience is felt both by teachers and stu- 

 dents from discrepancies and differences in successive editions of the same 

 work. To avoid causing such annoyance, M. Edwards possibly has 

 allowed this part of the work to occupy now no greater space than it did 

 fourteen years ago, when the lower invetebrate animals were comparatively 

 but little regarded. 



It must not, however, be supposed that all evidence of progress has been 

 suppressed. In some instances it has been indicated, though not fully dis- 

 played, as, for example, the connection between the Medusas and the Ser- 

 tularian zoophytes, opening up the debateable subject of the " alternation 

 of generations." This receives an illustration from the Biphora, marine 

 animals whose singular changes warrant the appellation happily bestowed 

 upon them, when M. Edwards tells us " ces animaux bizarres sont assez com- 

 muns dans la Me'diterranee." The affinity between the Polyzoa and the 

 tunicated molluscs is distinctly expressed, and both are grouped together 

 under the common term " Molluscoides." 



There are, however, cases in which statements, now known to be erro- 

 neous, continue to be given, without even a foot-note to warn the reader 

 of the changes in opinion which are consequent upon the advance of zoolo- 

 gical knowledge. Thus, at page 569, we read of coral islands which 

 appear to be based on the craters of extinct volcanoes. Yet Darwin had 

 completed his voyage in the Beagle in 1836; he had communicated his 

 observations on coral islands, and the true theory of their formation, to the 

 Geological Society of London, in 1837; and Sir Charles Lyell, in his 

 " Principles of Geology," seventh edition, published in 1840, had renounced 

 the old hypothesis, adopting the satisfactory and philosophical explanation 

 of Darwin. The first edition, therefore, of the " Cours Elementaire" con- 

 tained on this point the idea still current, but even then known to be erro- 

 neous, and this statement remains unchanged. 



We may adduce another example in corroboration of our remark. The 

 figure of the Argonaut appears with the expanded sails, and the " tiers of 

 oars on either side," according to poetic fable ; yet no information is given 

 regarding the habits of the animal, and the important functions performed 

 by the supposed sails ; and a doubt continues to be implied, if not expressed, 



