Bibliographical Notices. 393 



of Verrill, Lindstrom, and Hoseley (above noticed) as to the neces- 

 sity of abolishing the " Tabulata " as a distinct and separate divi- 

 sion of the Zoantharia ; and, further, that under the old name of 

 Tabulata there are included twelve distinct groups of Corals : some 

 of these are Hydrozoa and Zoantharia ; a large number may be 

 referred to the Alcyonaria ; but none are, probably, referable to the 

 Polyzoa. 



The twelve groups into which Dr. Nicholson proposes to divide 

 the Tabulata are the following — Milleporidae, Pocilloporidae, Favo- 

 sitidse, Columnariados, Syringoporidae, Auloporidae, Halysitidae, Te- 

 trariiidae, Thecidas, Helioporidae, Chaetetidae, and Labechidse. 



The first two groups, not containing any Palaeozoic representatives, 

 are but briefly noticed ; the far larger portion of the work (chaps. 2 

 to 14) comprises the results of the author's investigations of the 

 remaining ten groups. In chapters 2 to 6 (pp. 30-186) the author 

 enters fully into the characters, position, and affinities of the older 

 genera considered by him to belong to the Favositidae, and concludes, 

 after an extended study of their minute structure, that Prof. Yer- 

 rill and Dr. Lindstrom are right in referring all the corals usually 

 included under this head to the Z. perforata ; and while not pre- 

 pared to regard the group as a subfamily according to the views of 

 the above authorities, Dr. Nicholson gives his reasons at some 

 length for inferring that " a large number of the types are more or 

 less allied to the Poritidae, and some of which may perhaps be 

 capable of final removal to the latter family, but which really re- 

 present a series of separate though allied groups." 



Under the Columnariadae are provisionally placed a few Palaeozoic 

 corals ; but their precise position is uncertain, as the typical forms 

 exhibit certain Rugose features, while, on the other hand, they pre- 

 sent some conspicuous points of resemblance to the Astraeidae. 



With regard to the Palaeozoic family Syringoporidae, Dr. Nichol- 

 son does not agree with the opinion of Dana and others as to 

 Syrinyopora being allied to Tubipora, nor with Lindstrom that 

 it is a Rugose coral, but considers that this family is related to 

 the Favositidae, and should therefore find a place among the Z. 

 perforata. 



The family Auloporidae is considered to be in a chaotic condition, 

 so that it is impossible to come to any positive conclusion as to its 

 affinities or the forms it may contain, the materials in the author's 

 possession being insufficient for its clear elucidation ; but it may 

 probably be regarded as a peculiar group of the Alcyonaria. 



The Halysitidae, typified by the so-called "chain-coral," are sepa- 

 rated from the Syringoporidae, which were included with them by 

 M. -Edwards and Haime, and are stated to be nearly allied to the 

 Helioporidae, which they resemble in the general possession of two 

 sets of tubes, differing in size and in the position of their tabulae. 



The singular Silurian genus Tetradium, Dana, forms the family 

 Tetradiidae ; in general appearance it resembles some forms of 

 Ghcetetes, as C. radians, and in some characters is allied to Ffaly- 



Ann. & Mag. N. Hist. Ser. 5. Vol. iv. 28 



