December, 1910. 



KNOWLEDGE. 



4q5 



ZOOLOGY. 



Moiiograpli of the Land and FresIiK'ater Molliisca of the 



British Isles.— By ]OHK W.T.^Yi.OR. Part 17. Pages 225-304, 



and plates .\vi, xvii, xviii, xx, xxi and xxii. 



(Taj'lor Brothei^s. Price 7, 6.) 



In the present part of his monograph Mr. J. W. Taylor 



eighteen feet in length, a necklace of the shells, made by the 

 peasantry of Donegal, and a photograph showing the haunts of 

 a giant race of this species in Aran Islands, West Galvvay. The 

 snails live in the fissures of the limestone in which al.so the 

 true maiden hair fern grows in profusion. 



The Piei 



Froitt Taylof's Monogiap/i of the Land and Fvcslr.^'atcy Mtdljtsca. 



A necklace made by the peasantry of Donegal of the shells of 

 Helix nemoralis. 



Front Tavlor'i .l/.v;, >■■// . , .( . ■ ; .,.' .; 



A slime track of Helix iieiiiordlis. eighteen feet in length. 



completes his account of 

 Helix pomatia the so-called 

 " Roman snail " and gives a 

 coloured map of its distribu- 

 tion in this country, with 

 plates of some of the more 

 interesting variations in the 

 shell. The question of the 

 introduction of this, our 

 largest, snail into England 

 by the Romans is discussed. 

 The evidence which exists 

 for the contention is that its 

 shell is discovered among 

 Roman remains, and that 

 the animal is comparatively 

 abundant in a living state 

 near the site of several 

 Roman stations. On the 

 other hand the fact that an 

 allied species is the one that 



occurs in Italy is brought forward, but this is not 

 at all conclusive, as Helix pomatia occurs in 

 France, and it is from there that the Romans would 

 ha\e probably brought it. The fact that its fossilised 

 remains have been discovered in what are considered 

 to be undoubtedly pre- Roman deposits, however, 

 points to its being a true native of this country. 



Although considerable space is occupied with an 

 enumeration of named varieties of shells which even 

 many conchologists may think unnecessary, the 

 monograph contains a great many matters of 

 interest to zoologists and to general students of 

 nature. The present part is no exception, and wi 

 v.-ould allude to the descriptions of the habits of our 

 common snail. Helix aspersa, the cavities which it 

 wears in chalk and lime-stone rocks, its curious 

 homing instincts and its use for food, which arc 

 topics about Mr. Taylor has much that is valuable 

 to say. It has been doubtful also whether this 

 snail is indigenous, but a number of investigators 

 have shown that it occurs in the kitchen-middens 

 of neolithic times. 



The third species which comes in for considera- 

 tion is the handsome hedge-snail, //c'Z/.\' nemoralis, 

 and by the courtesy of the author we reproducr 

 three illustrations which are typical of those in the 

 monograph, showing a slime track of this species 



Mi>Uusca 



}iti(in of Malaria. — By RON.'^LD Ross. 669 pages. 

 36 illustrations. 6-in. X g^-in. 

 (John Murray. Price 21s. net.) 

 Though zoology, under which heading this 

 review is placed, can claim the credit of having 

 forged the weapons for conquering what is, 

 ]3erhaps, the most important of human diseases, 

 which kills on an average one million one 

 hundred and thirty thousand people in a year, 

 the subject of malaria is still, of course, a 

 iiH'dical one. Every biologist knows the name 

 ' if Ronald Ross, and in this book he summarises 

 the whole question himself, and has collected 

 tiigether the opinions of a score or more 

 other observers who have contributed chapters 

 dealing with their own investigations and 

 localities. We are given an outline of the 

 history of the disease which goes back over 

 two thousand years, of the discovery of the 

 parasite, of the determination of the way in 

 which infection takes place, of the recent history 

 of its prevention, and of all 

 the topics which bear on 

 the parasite, the course of the 

 disease, personal means of 

 combating it, and its public 

 prevention. 



Major Ross must be proud 

 of the work which he has 

 achieved, although there is 

 a note of bitterness in these 

 words which are taken from 

 his preface : — " The world 

 requires at least ten years to 

 understand a new idea, how- 

 ever important or simple it 

 may be. The mosquito 

 theorem of malaria was 

 at first ridiculed, and its 

 application to the saving of 

 human life treated with 

 neglect, jealousy and opposi- 

 tion." 



The haunt of a large variety of Helix iieinuralis m the Aran Islands, 



West Galway. 



