May 26, 1887] 



NATURE 



75 



structure of this form is worked out in the]| Report 

 with great care, and is illustrated by excellent figures 

 depicting for the first time the anatomy of the genus 

 as far as spirit specimens would admit of its demon- 

 stration. 



The Report enters fully into the geographical and 

 bathymetrical distribution of the species included in it. 

 Of these the Cyclostomata attain the greatest depth, 

 though only two of them extend to depths greater than 

 1000 fathoms ; namely, Crista elongata^ which was ob- 

 tained in the Australian region from a depth of 1450 

 fathoms, and Idmonea marioncnsis, which was brought 

 up from a depth of 1600 fathoms in the region of Ker- 

 guelen Land. It is a fact, however, by no means without 

 significance, as showing how little certain marine organ- 

 isms of even complex structure are dependent on depth, 

 that in the case of the last-mentioned species speci- 

 mens have been obtained from depths varying from 

 50 fathoms downwards. The Ctenostomata and Pedi- 

 cellinea are all from comparatively shallow water, none 

 having been obtained from a depth greater than 150 

 fathoms. 



No one could have been found better qualified than 

 Mr. Busk to institute a comparison between recent and 

 fossil Polyzoa. His work on the Polyzoa of the Crag is 

 among the most important contributions we possess to 

 the palaeontology of this group, and gives a special value 

 to his determination of the fossil relations of the species 

 collected by the Challenger. 



To the sub-order Cyclostomata belong the oldest fossil 

 Polyzoa as yet known, and out of the thirty-three species 

 of Cyclostomata obtained by the Challenger Mr. Busk 

 has been able to identify fourteen as occurring also in a 

 fossil state, thus proving the wide distribution in time of 

 even specific forms of this group. No fossil species has 

 as yet been identified with either the Ctenostomata or the 

 Pedicellinea. The negative evidence, however, which is 

 all that this statement expresses, proves but little, as 

 these groups are destitute of structures which might be 

 expected to continue recognizable in a fossil state. 

 Barrois, indeed, contends that the larval stage of the 

 Entoprocta (Pedicellinea) represents the primitive form 

 from which the whole of the Polyzoa have descended. Of 

 the Cheiiostomata— the sub-order to which the former 

 part of the Report is confined — no species has as yet 

 been proved to belong to Palaeozoic times, though this 

 group is] largely represented in Mesozoic and Tertiary 

 strata. 



The ten beautiful plates which illustrate this part of the 

 Report contain figures of all the newly-described species 

 of Cyclostomatous, Ctenostomatous, and Pedicellinean 

 Polyzoa, and bear ample evidence to the conscientious- 

 ness and accuracy with which all the details of form are 

 delineated. 



The purely descriptive part of the Report is marked by 

 all that judicious selection of characters, and succinctness 

 yet definiteness of diagnosis, which add so much to the 

 facility of comparison and to the practical value of any 

 work having for its object the determination and descrip- 

 tion of specific forms. The number and variety of the 

 species and generic types described and figured in this 

 and the former part of the Report give to the whole a 

 special value, not only as a record of the species collected, 



but as a faithful and comprehensive picture of the external 

 morphology of the important and interesting group of 

 organisms to which it is devoted. G. J. A. 



OUR BOOK SHELF. 



Dynamics for Beginners. By the Rev, J. B. Lock, M..A. 

 Pp.178. (London: Macmillan and Co., 1887.) 



This book is an attempt to explain the elementary prin- 

 ciples of dynamics in a manner suitable for school-work 

 with boys of ordinary mathematical attainments. Ac- 

 cordingly it contains a great number of easy iiumerical 

 examples, some worked out in illustration of the text, the 

 others arranged in groups at frequent intervals. There is 

 considerable freshness in these exercises, and they form 

 altogether a very useful series. 



The work is divided into four sections. The first treats 

 exclusively of rectilinear dynamics, thus avoiding at the 

 beginning of the subject all purely geometrical diffi- 

 culties. 



The second section introduces the notion of directed 

 or vector quantities, and deals with the application of the 

 parallelogram law to displacements, velocities, accelera- 

 tions, and forces in succession. 



Next we have a section on applications of the preceding 

 to projectiles, oblique impact, circular motion, and rela- 

 tive motion, concluding with a short chapter on the 

 hodograph. 



The final section deals with energy, work, and power. 

 These last three or four chapters read in connexion with 

 the first section would form a suitable first course in many 

 cases, involving no mathematics beyond a knowledge of 

 simple equations in algebra. 



The exposition throughout is remarkable for clearness 

 and precision of statement. The definitions of terms 

 seem particularly well worded. The names velo and celo 

 have been adopted for the units of velocity and accelera- 

 tion, and are used systematically in both text and 

 examples ; we hope these terms may win their way to 

 general acceptance, for the language of the subject gains 

 both in simplicity and directness by their introduction. 



The debt of gratitude which many teachers and students 

 already owe to Mr. Lock will be considerably increased 

 by this new class-book on a difficult subject, wherein it 

 appears to us that the skill and experience of the author 

 are displayed with great advantage. 



Journals kept in Hyderabad, Kashmir, Sikkim, and 

 Nepal. By Sir Richard Temple, Bart., M.P. Edited, 

 with Introductions, by his son, Richard Carnac Temple. 

 With Maps and Illustrations. Two Vols. (London : 

 W. H. Allen and Co., 1887.) 



The first journal contained in these volumes was written 

 at Hyderabad during the year 1867, when the author was 

 Political Resident at the Court of the Nizdm. It is 

 entirely political, and will interest only those who study 

 somewhat minutely the course of recent Anglo-Indian 

 history. The journals kept during visits to Kashmir, 

 Sikkim, and Nepal appeal to a larger class of readers. 

 They deal with the physical features of these countries, 

 and to some extent with social customs and institutions. 

 Most of the author's notes are too slight to be of much 

 scientific importance ; but all of them have the merit of 

 being written in a clear and unpretending style, and the 

 information contained in them is, so far as it goes, 

 thoroughly trustworthy. The introductions which the 

 editor has contributed to the book add very considerably 

 to its value. They are careful essays, in which Capt. 

 Temple has brought together a great many interesting 

 and suggestive facts that are not readily accessible to 

 ordinary readers. 



