102 



SCIENCE-GOSSIP. 



the various functions known as " dusting," " doing 

 out a room" and "the spring cleaning"; but 

 these as a rule only aggravate the evil. The 

 dust swept from the floor and furniture circulates 

 freely in the air. What little may cling to the 

 duster is, when the cloth is shaken at the window, 

 swiftly blown into the room again. The housemaid 

 at work is, as was recently stated in a medical 

 paper, indeed a sight suggestive of many evils. 

 " There she is on her knees, stirring up dust to her 

 own destruction and the detriment of everyone 

 else. Such dust as fails to find a resting-place 

 in her lungs, dances gaily about to settle down 

 again as soon as her work is completed." Some 

 enlightened individuals, it is true, use damp cloths 

 for dusting, and others seek salvation in tea- 

 leaves or covered sweepers. At best, however, 

 such luxuries are of trifling value. 



What is needed is a reform in house decoration. 

 Let our rooms be built with fewer angles and 

 projecting surfaces, the corners rounded off, the 

 floors rendered smooth, polished and impervious, 

 and the ceilings and walls painted. Above 

 all, let the amount of furniture be diminished, — 

 a check put upon our enthusiasm for curtains, 



carpets, pictures and drapery. Many other 

 provisions will suggest themselves, such as the 

 substitution of gas for coal, as a means of heating. 

 These, one and all, will help materially to improve 

 the character of the atmosphere that immediately 

 surrounds us. 



As regards clothing, too, a word is required. 

 The rough, fluffy materials so much in vogue 

 with both men and women keep up a brisk inter- 

 change of particles with the air. The amount 

 of clothing fibre in dust is enormous, and 

 probably only to be equalled by the quantity 

 of dust in an ordinary garment. On hygienic 

 grounds the use of napless fabrics, and of washing 

 materials has much to recommend it, whilst to 

 clothe ourselves in silk and satin is to confer a 

 benefit upon the race. Happily, the days of long 

 trains, and their accompanying clouds of dust, 

 are gone. In some ways at least dress is be- 

 coming more rational, a change due no doubt in 

 part to that dustiest of all recreations, bicycling. 

 Many other points of interest in connection with 

 the subject of dust, which want of space forbids 

 me to touch upon, will no doubt suggest them- 

 selves to the reader. 



ARMATURE OF HELICOID LANDSHELLS. 

 By G. K. Gude, F.Z.S. 



{Continued from page 71.) 



-pLECTOPYLIS polyptychia (figs. 55«-rf), from 

 -* Mount Licos, Cebu, Philippine Islands, was 

 described by Dr. von Mullendorff in the " Jahrbuch 

 der Deutschen Malakozoologischen Gesellschaft," 

 xiv. (1887), p. 272. The shell was figured in the 

 same volume (t. 8, f. 8) ; the armature, however, 

 was not figured, and I have pleasure in illustrating 



c d 



Fig- 55—Pltctopylis polyptychia. 



it. The shell is dextral, discoid, openly umbilicated, 

 finely and regularly ribbed above, finely striated 

 below, and horny-brown in colour. The spire is 

 scarcely raised and the suture is well impressed. 

 There are five and a-half to six convex whorls, 



which increase slowly and regularly, the last being 

 angulated above the periphery and scarcely descend- 

 ing in front. The aperture is diagonal, oblique and 

 heart-shaped ; the peristome is but little thickened 

 and reflexed, its margins are united by a raised 

 bilobed ridge at the parietal callus. The parietal 

 armature consists of two parallel, horizontal folds 

 revolving over one-third of the body-whorl, the 

 upper strong, and united to the raised ridge at 

 the aperture, which it bisects ; the lower thinner, 

 not reaching quite so far at the aperture (see 

 fig- 55 c )- The palatal armature consists of ten to 

 twelve denticles, arranged vertically in a row, eight 

 of which are larger than the rest, elongated hori- 

 zontally, and have one or two minute ones both 

 above and below them (see fig. 551?, which shows 

 the inside of the outer wall with its denticles). 

 The shell figured is in Mr. Ponsonby's collection, 

 and measures — major diameter, 4 millimetres ; 

 minor diameter, 3-25 millimetres; altitude, 1-25 

 millimetres. 



Plectopylis schistoptychia (figs. 563-e), from the 

 Chinese province Hoo-Nan, was described and 

 figured by Dr. von Mollendorff in the " Jahrbuch 

 der Deutschen Malakozoologischen Gesellschaft, 

 xiii. (1SS6), p. 1S5, t. 6, f. 2. As in the case of 



