724 



NATURE 



[August 4, 192 1 



closely resembling those found at Felixstowe, and 

 now in the British Museum. The bronze bowl further 

 contained part of an ivory armlet, two glass beads, 

 and a clay draughtsman. Altogether an exceptional 

 find that opens up a prospect of further successes on 

 the Suffolk heaths. 



Mr. E. E. Green contributes to the July issue of 

 the Entomologist's Monthly Magazine part vi. of his 

 "Observations on British Coccidae." In the present 

 article three species of Eriococcus are described as 

 new to science. E. glyceriae is based upon specimens 

 obtained from Glyceria maritima growing at Blakeney 

 Point, Norfolk; E, placidus was obtained from a 

 species of grass (? Festuca) at Thurnham, Kent; and 

 the third new species, E. pseudinsignis, occurred on 

 a similar food-plant in the same locality. Mr. Green 

 has added much to our knowledge of British scale- 

 insects during the past few years as the result of 

 painstaking field observations. Although the family 

 includes some of the most destructive of all insects, 

 the British forms, excepting the common mussel scale 

 and a few other kinds, are seldom observed unless 

 by the trained specialist. In the same periodical Mr. 

 J. E. Collin continues his descriptive keys of 

 Anthomyid flies of the genus Limnophora, Desv., in- 

 habiting our islands. 



An interesting article on the biology and genetics 

 of the very common ladybird beetle, Adalia biptinc- 

 tata, is contributed by Mrs. O. A. M. Hawkes to the 

 Proceedings of the Zoological Society for December, 

 1920. It is found that, although this beneficial insect 

 will devour many species of aphids, it will not, for 

 example, eat the common bean aphis except under 

 stress of circumstances. Difficulties were experienced 

 in the rearing of this and other species of ladybirds 

 in captivity owing to their cannibalistic habit of de- 

 vouring their eggs, larvae, and pupae. A. bipunctata 

 has many colour forms, and these varieties offer suit- 

 able material for the study of inheritance of normally 

 occurring variations. There is no evidence of domin- 

 ance in crosses between its two chief forms, the' red 

 and the black, but matings of red with red produced 

 only red with two exceptions. In matings of black 

 with black both red and black forms resulted, but it 

 was not possible to guarantee that the females had 

 not had partners prior to the experimental tests. 



Among the many activities of the late Mr. W. 

 Denison Roebuck, of Leeds, none was pursued with 

 greater determination than the collection of records 

 of the distribution of land and fresh-water mollusca 

 in the British Isles. Beginning in 1877, he was still 

 adding fresh data up to his death in 1919, and the 

 summary results of the 59,000 entries in his books are 

 published in the last issue of the Journal of Concho- 

 logy (vol. xvi.. No. 6). No record was admitted to 

 his "census" unless specimens had been seen and 

 verified by referees appointed by the Conchological 

 Society. The distributions ascertained by this accurate 

 and painstaking work are set out in tables under 

 153 topographical divisions based on those devised by 

 H. C. Watson, and are also shown for more than 

 150 species in five plates of small, but clear, maps. 

 The whole forms an account which should be of sub- 

 NO. 2701, VOL. 107] 



stantial value not only to conchologists, but also to 

 students of geographical distribution. It is to be 

 hoped that its publication will stimulate naturalists 

 to deal with other groups in the same way, and by 

 collaboration render the enormous mass of data which 

 must exist in individual collections of more general 

 service. British entomology suggests itself particularly 

 as a field in which important results might readily 

 be obtained by systematised effort. Copies of Mr. 

 Roebuck's work may be had from Mr. J. W. Jack- 

 son, University Museum, Manchester, at 55. each. 



A MEMORANDUM to the Government of India regard- 

 ing the probable amount of monsoon rainfall in 192 1 

 was issued by Dr. Gilbert T. Walker, Director-General 

 of Observatories in India, dated June 7, 1921. The 

 monsoon rainfall is affected by previous conditions 

 over different parts of the earth, and these conditions 

 have been on the present occasion unusually diver- 

 gent. In India the development of the monsoon on 

 the western side of the Peninsula had up to date been 

 less vigorous than usual. Examining one of the 

 features of interest, it is shown that scarcely any 

 snow fell during the preceding winter in Baluchistan 

 and very little on most of the hills of the North-West 

 Frontier Province. The total winter precipitation over 

 these areas is said to be the lowest for at least twenty 

 years. Dr. Walker summarises the conclusions to be 

 drawn from the controlling features with a statement 

 that it would be unjustifiable to attach any import- 

 ance to indications so feebly marked as those of the 

 present year, and he adds that when their restiltant 

 effect is so trifling nothing is gained by attempting 

 to reach a conclusion, and he does not consider the 

 controlling factors decided enough to enable a trust- 

 worthy forecast to be prepared. 



So far as efficiency and durability are concerned, 

 there does not seem much to choose between the 

 electrical and the mechanical methods of connecting 

 the propellers of a ship with the steam turbines. 

 Excellent results have been obtained by both methods. 

 The electrical method, however, has much greater 

 flexibility. There is no necessity to have the tur- 

 bines near the shaft, and its direction of rotation can 

 be reversed with the greatest ease. In La Nature for 

 July 16 L. Jauch, the chief mechanician of the French 

 Navy, compares the two methods, and concludes that 

 the electrical drive will be much the more popular in 

 the future. He points out that five battle-cruisers each 

 requiring 180,000 h.p. and using electrical methods 

 of driving the propeller are being built in America. 

 The author calculates that at maximum power the 

 efficiency of the mechanical type of gearing would be 

 2 per cent, higher. But this is offset by a 2 per cent, 

 gain in favour of the electric drive at mean speeds 

 and a 20 per cent, gain at low speeds. He points out 

 that with the electric drive there is no fixed relation 

 between the speed of the propeller and the speed of 

 the steam turbine. Hence the latter can always be 

 run near the speed at which its efficiency is a 

 maximum. 



The Department of Commerce, Bureau of Stan- 

 dards, Washington, has just issued Circular Paper 

 No. 100 on "Nickel" (20 cents). This is one of a 



