on Zoology and Botany. ~ S21 



siibtus olivaceo-crocea ; scapulis, iiropygio, strjgaque lateral! a rostro ad 

 pectus descendente nitide violaceis ; jugulo castaneo ; cauda nigra. 



Plates 1-^2 and 1~3 contain four uncommon varieties of the true A. 

 v'lrginea {Bulla virghiea, Lin.), under which name so many shells have been 

 placed. Mr. Swainson's definition of the characters which belong to this 

 variable species, is as follows: — A. vlrgiuea, testii elongata, fasciis numerosis 

 nigris viriilibus et flavis ornata ; anfractus basalis latitudine altitudinem su- 

 perante; apertura rotundata labio exteriore integro ; basi proftinde emar- 

 ginata. — Lici/;(fl! crkia, Sw. : the male and female of this insect differ in a 

 remarkable manner, and had not observations been made on the living in- 

 sects, we should almost have doubted their connexion. 



Greville^s Scottish Cryptogamic Flora. 

 Mr. Greville's last No. (4) contains the curious Echinella fasciculata, 

 which by many would be considered of animal origin ; but which, as neg- 

 lected by the zoologist, we are happy to see (whatever may be its real na- 

 ture) taken up by the botanist : Puccinia Btuci : Amanita nivalis, a delicate 

 new species which well merits the name, whether we consider the snowy 

 whiteness of its hue, or its truly alpine situation among the snow of the 

 highest of the Grampian Hills : Uredo cffusa (the U. Sjnraice of Sowerby) : 

 and a new species of Na'ynaspora, K. Rosarum. Under this last individual 

 we have an observation, " that the Genus Namaspora may be found even- 

 tually to border too closely upon many species of the old Genus Sj^lntiia.'" 

 The justness of this remark will be apparent to those who will trouble them- 

 selves to compare the excellent magnified section of the Na;vi. Rosanmi 

 with those of Cryptospharia Taxi, (Spharia Taxi of Sowerby,) figured in 

 Mr. Gre\ille's 3d Number. It is by such admirable analyses of the parts of 

 fructification of these obscure plants, that we may expect much new light to 

 be thrown upon the subject. 



LXI. Intelligence and Miscellaneous Articles. 



LAW OF CALORIC STATED BY M. LAPLACE. 



An an inquiry on the attraction of spherical bodies and the repnlsion of 

 elastic fluids, M. Laplace vuifolds in the Annates de Chimie, xviii. 185 seq., 

 the following remarkable law agreeing with experiment : 



" The quantity of heat which is disengaged from a bulk of gas passing 

 under a determined pressure from a higher into a lower temperature, is pro- 

 portional to the square root of this pressure." 



This accounts, among other things, for the great advantage of high pres- 

 sure steam-engines ; the pressure which the steam exerts being propor- 

 tional to the caloric contained in a given space, which may be considered as 

 an unity ; the pressure or tension of the steam increases in a much greater 

 ratio than tiie quantity of caloric, that is to say, fourfold, while the caloric 

 is doubled. 



DI6TRIUUTION OF TEMPEUATUllE IN METALS BY MECHANICAL 

 CONCUSSION. 

 It is well known that carters are in the habit of well hanmiering the axles 

 of tiieir waggons, before they put them in motion in ii hard frost, in order 

 by tliis means to guard the iron which has become brittle against breaking. 

 The utility of this practice in great and sudden changes of temperature ia a 

 metal becomes obvious, if we rcci>llect that in Laplace's and Lavoisier's ex- 

 periments on the expansion of metallic rods, these rods would only take 

 an uniform tem])erature in their whole length when they had been subjected 

 to percussion. Aim. dc Cliiiii. xviii. 3."). 



Vol. 60. No. i!94. Oct. \ii2'2. S s OBSER- 



