76 Bibliographical Notices. 



attachment of one species of Productus (p. 457), by the twisting of 

 some of the spines of the ventral valve ronnd the column of a 

 crinoid, we may mention that Prof. King, in 1850, had shown that 

 some forms of Strophalosia were attached to other bodies by their 

 long umbonal spines. 



The Gasteropoda, Pteropoda, Heteropoda, and Cephalopoda are 

 described in the same manner as the preceding orders of Hollusca. 

 Under the Cephalopoda a classificatory table is given, adopted by 

 M. Pavre, which is primarily based on the presence or absence of 

 an aptychus, with the new subgeneric names introduced by Waagen, 

 Suess, and others for the comprehensive genus Ammonites, wbich 

 hitherto have not been introduced into text-books. Although now 

 accepted, " it must be admitted that it is generally impossible to 

 refer particular specimens to these sections, unless they are in a 

 state of unusually complete preservation, or the observer be pro- 

 vided with a very extensive suite of examples of a given form." 



In treating of Eozoon the author speaks with caution, although he 

 gives fully the characters by which its organic nature has been 

 recognized. While briefly alluding to the opinions as to its non- 

 organic origin, Dr. Nicholson does not consider that the arguments 

 of Mobius are by any means decisive. 



Under the Ccelenterata the division " Tabulata" is still retained. 

 Although, as stated in this work and the separate memoir on 

 the same group noticed in this Journal (Nov. 1879), from the 

 researches of Verrill and Moselcy, the " Tabulate Corals " are a 

 most diverse group, and have reference to a structure not charac- 

 teristic of any natural one, still, says Dr. Nicholson, "there remain 

 some extinct groups of corals which may, in the meanwhile, be 

 retained to form the section Tabulata, though their true affinities 

 and systematic position are matters of great doubt " (p. 199). 



Codaster and Codonites, which make a close approach to Pentre- 

 mites, are placed in the Cystoidea, as advocated by Billings, and 

 may be regarded as transitional forms between that order and the 

 Blastoidea, and thus extending the range of the Cystideans to the 

 Carboniferous. In describing the older fossil Polyzoa, the author 

 makes some remarks on the position of some fossils referred to Ohce- 

 tetes, Monticulipora, &c. ; some of the forms described under these 

 names he considers really Polyzoa, while the tabulate forms of 

 these genera may be regarded as being Actinozoa. The Secondary 

 and Tertiary Polyzoa are so numerous and varied that only a brief 

 and general review of the leading groups is given. The structure 

 of Heteropora is described at some length, as it is considered to have 

 an important bearing on the structiu'e and systematic position of 

 Chastetes, Fistulipora, &c. 



Under the Mollusca it might have been useful to have given the 

 sectional divisions of the important genera Trigonia and Inoceramus, 

 and also of Nerin&a. It may be noticed that Atiomia and Cyrena 

 occur in the Jurassic strata ; and that the subgenus Trivia, typified 

 by Gyprcea europaxt, stated not to occur in a fossil condition (vol. ii. 

 p. 22), is found in the Crag deposits. 



