204 NATURAL SCIENCE. March, 



for a scheme of classification of the Mollusca, that he should have 

 given a hopelessly out-of-date tabular view of the orders, etc., and 

 have copied an unworkable diagram to explain the "visceral loop." 

 The old and erroneous theory of the iridescence of nacre being due to 

 lines of outcropping laminae, with the popular misreading anent 

 Brewster's button, once more makes its appearance, although a 

 balancing sentence is inserted in part ii., where the subject is again 

 brought forward, showing that the author evidently had his mis- 

 givings. For the system of bestowing extra or varietal names on 

 what may be termed normal variations and on monstrosities, no word 

 of condemnation is too strong. Again, why give to each figure of a 

 shell the name of the collector, while the author of the anatomical 

 diagrams is unacknowledged, whereas he at least has done something ? 

 ^^ Pereger,'" we might hint, is considered by the best classical authori- 

 ties to be a substantive and not an adjective; hence " Limncra peregva " 

 is not permissible. The nomenclature in other places is, we suspect, 

 not above question, but that will be better seen when the systematic 

 portion comes to hand. Many other major and innumerable minor 

 points for criticism abound, but there is so much downright honest 

 work to be grateful for that naught more shall be said, save to suggest 

 that Mr. Taylor would do well to keep a closer eye on Natural 

 Science if he wishes his work to be up to date. 



A first cause for gratitude strikes the eye immediately on opening 

 the book : it is the abundance of new, and, with few exceptions, 

 excellent illustrations. They are so admirable that their frequent 

 repetition is by no means a matter for resentment. The coloured 

 plates, also, are far and away the best of their kind that have 

 appeared in any English — we beg pardon — British work on the 

 subject : their defects are those inherent in chromo-lithography. Of 

 the text as a whole it is scarcely possible to speak till more be 

 finished, but Mr. Taylor in those portions of his work where he is 

 thoroughly at home expresses himself both clearly and well. 

 Occasionally there is a repetition, as in the account of the iridescence 

 of nacre, and in the description of the hypothesis of hyperstrophy 

 (pp. Ill, 112). This last subject is, however, very well handled and, 

 moreover, may be quoted as evidence of how anxious the author is to 

 do ample justice to his theme, since internal evidence shows that 

 when the first part was written he still retained the impression that 

 Planorbis was a dextral form, and changed his views later, owing, 

 probably, to the appearance of Vanstone's paper in the Proceedings of 

 the Malacological Society of London. Hyperstrophy and hetero- 

 strophy are, it may nevertheless be remarked, a little out of place 

 under the heading " Monstrosities." 



The work when complete will be one that cannot fail to be most 

 serviceable to all varieties of conchologists, and we doubt not that 

 the appearance of each future part will be eagerly looked forward to 

 by all, more especially by those who, being distant from any good 

 museum, require a well-illustrated guide such as this to aid them in 

 their studies. B. B. W. 



The Permian Vertebrata of Bohemia. 



Fauna der Gaskohle und der Kalksteine der Perm-formation Bohmens. 

 By Dr. Anton Fritsch. Vol. iii., pt. 4, pp. 105-132, pis. 123-132, with title- 

 page and index to vol. iii. Prague: Fr. Rivnac, 1895. 



In reviewing the last part of Dr. Fritsch's well-known work on the 

 Bohemian Gas-coal (Nat. Sci., vol. vi., 1895, p. 132), we referred to 



