392 Bibliographical Notices. 



belonging to this group has become of considerable interest and im- 

 portance, both as regards their general structure and zoological 

 position. As to their affinities, considerable difference of opinion 

 prevails on some important points. Formerly regarded as true Zoan- 

 tharia, it now appears doubtful, from recent investigations, whether 

 most of the forms so assigned belong to that group. In fact, says 

 Mr. H. N. Moseley (1876), "it would be as well if the term Tabu- 

 lata were dropped altogether, since it has reference to a structure 

 common to certain Alcyonaria, Zoantharia, and Hydroida, and, being 

 not characteristic of any natural group, only tends to confusion." 



Twenty years ago (1859) Agassiz suggested the hydroid nature of 

 Millepora, which view, adopted by Clans and others in Germany, 

 and by Dana in America, was only partially accepted. M.-Edwards, 

 in the following year (1860), did not consider the facts on which 

 this opinion was formed sufficiently ascertained; and Prof. All- 

 man has recently expressed some uncertainty on the subject. With 

 the exception of Prof. Verrill (Ann. & Mag. Nat. Hist. 1872, vol. ix. 

 p. 355), no one had examined the soft parts of any of the Tabulata, 

 until the critical investigations of Mr. Moseley were communicated 

 to the Royal Society in 1876, in which he states, " though no evi- 

 dence as to the structure of the generative system of Millepora was 

 obtained, the results yield convincing proofs that this interesting form 

 is a true Hydroid ;" and the subsequent still more elaborate paper on 

 the Stylasteridse (the Croonian Lecture, 1878) has further eluci- 

 dated the subject, by showing that this family, with the Milleporidse, 

 should form a suborder, the Hydrocorallina. 



Besides the Milleporidee, Agassiz believed that the Eavositidse, and 

 all the other species of which the septa are not continued vertically, 

 ought not to be classed with the Corals — an opinion combated by 

 Verrill and doubted by M.-Edwards ; while M. Dollfus classed some 

 genera of the Tabulata with the Hydroida, and the Chaetetidae and 

 Favositidoo, he considered, were allied to certain forms of Polyzoa. 



Prof. M. Duncan, in 1871 (Rep. Brit. Assoc), treated of the 

 structure and affinities of the Tabulata, still retaining them among 

 the Zoantharia, classing them into two principal and five minor 

 groups, but considering some genera, as Chcetetes and similar forms, 

 to be allied to the Alcyonaria. 



The object of Dr. Nicholson in the work under notice is an attempt 

 to elucidate the minute anatomy of the principal Palaeozoic genera, 

 which he has personally investigated ; and this has been chiefly 

 effected by means of microscopic sections ; so that the present work 

 is more extensively occupied with detailed descriptions of minute 

 structure than treatises on fossil corals usually are ; and well- 

 known types have generally been selected for study. 



The first chapter is devoted to the affinities and classification of 

 the Tabulate corals, and also contains a concise historical sketch, 

 showing the principal tendencies of the more recent researches of 

 naturalists and palaeontologists with regard to this group of corals. 

 The investigations of the author lead him to corroborate the views 



