Revieus — M. C. Klemenfs Origin of Dolomite. 329 



as we get here the first figures of many new genei'a founded by the 

 authors among the articulated Brachiopoda in the course of their 

 successful labours. We heartily congratulate them on the results, 

 and can only express the hope that the publication of the quarto 

 edition of the Plates needed to complete their great work will not 

 be again delayed by " malign influences " and lack of fiscal support. 



An alphabetical index to genera and subgenera is appended, in 

 which we note Mr. W. D. Mathews' siphonotretoid genus Trema- 

 toholus is not included among the synonyms, although it is omitted 

 from the generic list classified into families in the " Systematic 

 Classification " with which this most useful and interesting hand- 

 book concludes, and to the main features of which, through the 

 courtesy of the authors, we have already referred (see Geol. Mag., 

 March 1895). 



With regard to systematic classification, however, and the vexed 

 questions of genetic relationships and affinities, the last word has 

 by no means been said. There is still room here for diversity of 

 opinion, more especially in connection with the relationships of the 

 primitive forms which present such a mixture of characters. Mr. 

 Charles Schuchert, we learn, has nearly completed a " Catalogue 

 of Brachiopoda," which, we feel sure, will further illuminate this 

 most difficult subject. New genera and species are almost daily 

 described throughout the world. Dr. W. H. Dall has a paper in 

 the press defining seven new recent forms fi'om the Pacific Ocean, 

 one belonging to a new subgenus of the Rhynchonellidje of a very 

 interesting type.^ The full history of that widespread deep-water 

 discinoid, the so-called Discinisca Atlantica, still remains unwritten. 

 A grand opportunity awaits a well-trained embryologist who would 

 turn his attention to the developmental history of the living British 

 Cranoids and Discinoids. Such an investigation, if successfully 

 carried out, might throw much light on obscure points in the early 

 history of these ancient stocks. Will no British student do for our 

 Cranoids and Discinoids what Morse, Dall, Brooks, Beyer, and 

 Beecher have done for the Terebratuloids and Linguloids of the 

 American shores? Palfeontologists would owe him a debt of grati- 

 tude, and science be greatly advanced thereby. Agnes Crane. 



III. — SuR l'origine de la Dolomie dans les formations sedi- 

 MENTAiRES. Par M. C. Element. Bull. d. 1. Societe Beige 

 d. Geol., etc. Tome IX (1895), pp. 3-23. 



AFTER reviewing the very extensive literature relating to v 

 the mode of occurrence and origin of dolomite, the author 

 describes a series of experiments in which a solution of sulphate 

 of magnesium and chloride of sodium is made to act at various 

 temperatures on arragonite and calcite. He finds that in the 

 presence of a saturated solution of common salt at a temperature 

 of 91° C. sulphate of magnesium will act on the powder of 



1 Frieleia Halli, Dall, a smooth Pacific species allied to Eemithyris (?) lucida, 

 Gould, from Japanese waters. 



