520 Reviews — A. R. Hunt — Ripple-marks and Waves. 



the former, says the author, may be derived from the latter by 

 arrest of development, which, however, has affected the soft parts 

 more than the more simply organized shell. Though this hypothesis 

 is advanced "with all reserve," it is so briefly and prettily expressed, 

 that an elementary student might easily be induced to adopt it. 



The preceding volume of this work, dealing with the Palaeozoic 

 fauna, was issued in 1883; the first part describing the Tertiary 

 Mammalia was published in 1878, and has long since been out of 

 print. 



If Prof. Gaudry, instead of merely republishing that book, would 

 prepare a similar volume to the present one, dealing with the whole 

 Tertiary fauna, he would still further add to the feelings of 

 gratitude that must be entertained by all who are interested in the 

 popularization of palaeontology. 



In conclusion, we cannot speak in too high terms of one who 

 has, like Prof. Gaudry, devoted his life to the exposition and 

 illustration of palaeontology, and whose numerous original researches 

 and publications upon the fossil Mammalia of Attica, of Mont 

 Leberon, and other localities, have won for him the highest scientific 

 reputation. 



II. — Researches on Ripple -maeks and on Wave -action. By 

 A. R. Hunt, M.A., F.L.S., F.G.S. 



GEOLOGISTS have given their attention to the subject of Modern 

 as well as Ancient Sea-beaches, but they have not occupied 

 themselves very much with the present state of the Sea-bottom 

 extending from low-tide mark to 40 or 50 fathoms. Submarine 

 researches are, however, capable of affording much valuable informa- 

 tion to geologists, not only on the character of the rocks that may 

 form the sea-bed beneath recent deposits, but also on the nature 

 of the deposits now forming and the influences that affect them. 

 For a number of years Mr. A. R. Hunt, of Torquay, has devoted 

 himself to researches on these subjects, principally along the coast 

 of South Devon, and he has thrown considerable light on the nature 

 of the rocky floor in certain places, from the evidence of a number 

 of trawled blocks. 1 It is, however, to his observations on Ripple- 

 marks and Wave-action that we wish now to direct attention ; and 

 as these subjects appeal, also to the mathematician, he has sought 

 aid from Sir G. Stokes and Lord Rayleigh. In 1882 he constructed 

 an experimental tank to test his observations on the production of 

 Ripple-marks, and his conclusions are that they are due to wave- 

 currents, and are independent as a rule of tides and tidal currents. 

 The sand-ripples on beaches are made by alternate currents set up 

 by waves, and those laid bare by the fall of the tide may often be 

 distinguished from the Ripple-marks made at greater depths. The 

 shore Ripple-marks are usually imperfect through loss of their sharp 

 ridges. Wave-currents make ripples with equal sides; continuous 

 currents, or continuous currents disturbing wave-currents, make 



1 Notes on the Submarine Geology of the English Channel off the Coast of South 

 Devon, Trans. Devon. Assoc. 1880-89. 



