364 THE NATURAL HISTORY REVIEW. 



an irregularly shaped spot, which is bounded by a narrow ribbon of 

 colour. This peculiar character of the axis, is explained when the 

 first development of the coral has been properly studied. It is then 

 seen, that the calcareous matter is at first deposited in the form of a 

 single lamella, or sometimes of three or four of them united, around 

 which the successive layers are placed, and these lamellaB, in a cross 

 section, present the appearance above described. Other points in 

 the structure are commented on, and some reference is made to the 

 probable cause of the variety in the tint of the coral, but the author 

 can only assume that, as in the case of shells, there are periods 

 when increase in size, and rapid secretion of colouriog matter are 

 evidences of renewed vital activity, so in the coral, times of exhaus- 

 tion and vigour may be indicated by the different degrees of colour 

 found in the calcareous layers. 



The chapters on the Eeproduction and Development of the Coral 

 are the most important in this work, not only from a physiological 

 point of view, but from their containing valuable information bear- 

 ing on the special object of M. Lucaze-Duthiers' inquiries. Nearly 

 eighty pages are devoted to those parts of the natural history of the 

 coral. 



Beginning with the distribution of the sexes, the author points 

 out the great diversity of arrangement he found to exist. Each polyp- 

 mass was usually found to be either unisexual, or with both sexes 

 present, but confined to separate branches ; occasionally males and 

 females were found intermixed, and in a few cases, hermaphrodites 

 were discovered, but these were very rare. No external distinction 

 was observed, and an examination of every polyp was necessary in 

 order to establish the character of the whole group. This variety 

 in the distribution of the sexes, appears to be common among polyps 

 in general, but hermaphroditism is undoubtedly more frequent in the 

 simpler forms. With reference to the reproductive organs, which 

 are described at some length, and their various histological charac- 

 ters pointed out, we need only remark that the number of these 

 organs in the coral, appears to be considerably less than among the 

 Actinoid polyps, but they have a more marked and definite charac- 

 ter, and, when mature, occupy a larger portion of the general cavity 

 of the body. The spermatozoa were not found to possess any spe- 

 cial or exceptional form, and every grade in their development was 

 to be met with in the contents of a single testis, although the testes 

 themselves are successively matured. On the question of impreg- 



