SHELLS. 



lyinff on the fea-ftiore, make an excellent manure for cold 

 clayey lands. See Sand and Clay. 



It IS likewife a term applied to the light calcined pieces of 

 calcareous ftones, which have been converted into lime ; and 

 alfo to the rind of turnips fcooped by fheep, which are 

 moftly applied to the purpofe of feeding the ftore-iheep. 

 See Lime and Turnips. 



SuELL-Jppk, in Ornithology, an Englilh name for the 

 loxia or crolsbill, given from his manner of fplitting an 

 apple, and feeding on the kernels, leaving the fhell of the 

 pulp untouched. 



SHELL-Draie, a common Englilh name for the tadorna. 



SHELL-Fi/h, a collcAive name for filhes naturally inclofed 

 in (hells. Thefe animals are in general oviparous, very few 

 inftances having been found of fuch as are viviparous. 

 Among the oviparous kinds, anatomiits have found that 

 fome fpecies are of different fexes in the different individuals 

 of the fame fpecies, but others are hermaphrodites, every 

 one being in itfelf both male and female : in both cafes their 

 increafe is very numerous, and icarcely inferior to that of 

 plants, or of the moft fruitful of the infeft clafs. The 

 eggs are very fmall, and are hung together in a fort of cluf- 

 ters by means of a glutinous humoui", which is always placed 

 about them, and is of the nature of the jelly of frogs' 

 fpawn ; by means of this they are not only kept together 

 in the parcel, but the whole duller is fallened to the rocks, 

 fhells, or other folid fubllances, and thus they are preferved 

 from being driven on Ihore by the waves, and left where 

 they cannot fucceed. 



SHELL-Ga/l-In/eS,?Ln infeft of the gall-infeft clafs, fome- 

 what refembling thofe which are calkd the boat-fafhioned 

 ones, but differing in this, that as the two ends of that fpe- 

 cies are not very different in form, in this kind one of the 

 ends is fharp and pointed in comparifon with the other. 



It has its name of flicll-infedl from the refemblance it bears 

 to a mufcle-fhell ; as it is, in its whole form, not unhke one 

 of the two fhells in which the common fea-mufcle is in- 

 clofed, but the pointed end of this infeft is much more ex- 

 tended in length than the fmaller end of this fhell. 



This fpecies is extremely fmall, and may be eafily miftaken 

 for the minute cafe out of which fome fmall infeft has 

 efcaped ; or in another ftate, for the nell in which fome 

 fmall infeft had depofited its eggs ; but if the alTiftance 

 of the microfcope be called in, they will eafily be difcovered 

 to be true gall-infefts, even as foon as they are hatched from 

 the eggs. This fpecies, at its full growth, is fo fmall, that 

 it requires good eyes to difcover it : it is brown, very fmooth, 

 and polifhed on the furface, and much of the colour of the 

 bark of fome trees ; it has ufually an edge of a cottony 

 matter, vifible where its fides touch the tree, and its eggs 

 are always depofited on a fine cottony bed ; the young ones 

 are white, flat, and have two fmall horn?, and fix legs ; in 

 this flate they are known to be of the gall-infeft clafs, not 

 by their likenefs to their parent, but to the young gall- 

 infefts of other fpecies. They march about very brillvly for 

 fome time after they are hatched, and after that fix them- 

 felves, and then begin to grow, and by degrees alter their 

 form, till they at length are of the fame fhape with their 

 parent. Reaumur, Hift. Inf. torn. iv. p. 69, 70. 



SHELL-Mar/e, in Agriculture, a fubftance of ilic m. rly 

 kind, which is of a flaky or (helly nature. Though Mr. 

 Marthall has not feen this material made ufe of in any of 

 the fouthern parts of this country, he fuppofes it highly 

 probable, that in the more northern counties it maybe found in 

 confiderable quantity ; and that in different parts of Scotland, 

 it ia in common ufe as a manure. And he confiders it as ufually 



found in low moift fitiiations, under what is termed bog- 

 meadow, a fort of half-reclaimed morals ; namely, tough, 

 coarfe fward, formed upon a depth of black moory earth, 

 which reits on the marie : this being, in fome inftances, feve- 

 ral feet in depth. In refpeft to appearance, the colour is 

 nearly white. Its confiftence, in the pit, is that of foft 

 curd, roughly broken ; with the perceptible remains of 

 fmall Ihells interfperfed among it ; and generally with fome 

 portion of earthy particles. It was found by analyfis, that 

 one hundred grains of a fpecimen taken in 1793, fro™ the 

 extraordinary pits on the eftate of Auchtertyre, belonging 

 to the late fir WiUiam Murray, on the fouthern fliirts of the 

 highlands of Perthfhire, yielded eighty-two grains of cal- 

 careous earth : the refidue being brown earthy matter, 

 mollly, it is probable, animal mould, with a flight intermix- 

 ture of vegetable fibres. One hundred grains, taken from a 

 pit in Strath Tay, within the central highlands, yielded 

 feventy-four grains of chalk ; the refidue being fimilar to 

 the above. The fearch for this fpecies of marie is fo obvious 

 and eafy, that nothing but -unpardonable negleft can fuffer 

 a quantity of it to remain within an eftate (fituated in a 

 country where it is known to abound) unknown to its ma- 

 nager. Wherever, in vallies and dips of furface, level 

 water-formed lands (whether they are already f warded over, 

 or yet remain in a flate of morafs) are found, there infert the 

 borer : not in one place only, but in various parts of it, that 

 no hollow receptacle of marie may be miffed by the farmer. 



And with marles of the folTile kmds it is remarked, that 

 where, by analyfis, the proportion of chalk is found to be 

 fmall, as not more than one- third of the whole ; if the 

 earthy matter with which it is combined appears to 

 be of a rich fertilizing nature, fuch marie becomes, he 

 thinks, a proper fubjeft of trial in the field. And a good 

 method for making this fort of trial, is to fpread the marie, 

 at a leifure time, as in winter, or the early part of fummer, 

 upon grafs-land ; and catching a favourable opportunity, 

 when the foflil is in a mellow friable ftate, between wet and 

 dry, to break down and fpread the lumps, with the roller 

 and harrow, to give freedom to the grafs, and an opportu- 

 nity of gathering off the ftones and rubbifh, which may 

 have been carried on with the marie ; and in order that fum- 

 mer fhowers may wafh the finer parts of it down into the 

 foil, while it is open to receive them ; repeating the opera- 

 tion as often as it may be required. And he knows no better 

 method than this, by which to apply marles, on a large 

 fcale, in praftice. 



SHELL-SatiJ, a name given by the farmers, in fome part* 

 of England, to the fragments of Ihells found on the fea- 

 fhores, and ground to a fort of powder, fo that they refera- 

 ble fand. See Manuring. 



There is alfo another kind, ufed as this is, in fome parts 

 of Cornwall, and compofed of fragments of a fort of ten- 

 der white coral. This is found principally about Falmouth, 

 and is called by the fame name of fhell-fand, though very 

 improperly. All the kinds are of great ufe in agriculture, 

 but they are differently cfteemed by the farmers, as they 

 are more or lefs rich, which they know by their colours : 

 the reddifli kind is efteemed moft of all ; next to this the 

 blue is judged the belt, and after this the white. Such 

 as is dredged up from under the water, is always found 

 better than fuch as is found dry on the fhores ; and fuch as 

 is entirely compofed of fliells is to be chofen, rather than 

 fuch as has fragments of ftone among it, which is a yery 

 common cafe. See Sand, and She/ly Sand. 



Shell-7"oo;/W, in the Manege, an appellation given to a 

 horfe that from four years old to old age, naturally, and 



without 



I 



