326 GEOLOGY AND MINERALOGY. 



blow-pipe characters are very peculiar. Of course the so-called Saussurites of 

 many authors are still to be looked upon as mere feldspathic or rock mixtures. 



Uranite. — M. Descloizeaux, in a long and valuable communication {8ur I'Emploi 

 des Froprietes Optiques Birefringentes, jyour la determination des Especes cris- 

 tallisees : le. memoir e) published in the 5th part, for 1858, of ih.& Annales des 

 Mines, announces the Uranite of Cornwall and Autun to belong to the Tri- 

 metric system of crystallization. This fact, first revealed bj optical characters, 

 ■was confirmed by the actual measurement of crystals. The crystals examined, 

 although apparently combinations of tri-axial and bi-axial Dimetric pyramids 

 with the largely developed basal plane, proved to be combinations of the latter 

 with a rhombic octahedron and two domes, a macrodome and brachydome. The 

 measured difference was, however, exceedingly slight. The base on the macrodome 

 gave 109°6', and on the brachydome 109°19'. The calculated prism-angle, also, 

 only differs from a right-angle by 43', so that M. Descloizeaux's determination 

 must be considered to rest pi'incipally on optical characters. If, as maintained by 

 M. Descloizeaux, Uranite and Chalkolite belong really to different systems, we 

 strongly suspect that this will be found to apply to certain specimens only, in 

 which the water atoms depart from the normal eight-atom type ; and that, if Tri- 

 metric Uranites occur, Trimetric Ohalkolites -^iW be found also. 



Liroconite (^Linsenerz, Wern). — This mineral, hitherto regarded as belonging to 

 the Trimetric system of crystallization, is stated by Descloizeaux (loe. cil.) to be 

 Monoclinic. He makes the prism-angle (oo: co)=74°21', and the axial inclina- 

 tion==91''27' and 88°3y. 



RIB FORMULA IN BEAOHIOPODS. 



At an evening meeting of the Canadian Institute, and afterwai'ds in a note 

 inserted in the January number of this Journal, we described a convenient method 

 of denoting the number and situation of the ribs or plications on Brachiopod shells. 

 In doing so, Ave were altogether unaware that a plan of a similar character had 

 been previously adopted. "We have since found, however, that a method essenti- 

 ally the same, was employed incidentally by Professor Hall, in his description of 

 Orthis [Delthyris) lynx. We hasten, therefore, to make this acknowledgment, 

 and to disclaim any intentional piracy. The method proposed by us, is merely an 

 extension of a plan already followed, although, we believe, only in the instance 

 referred to above, by Professor James Hall. This will be seen by the subjoined 

 extract from Professor Hall's description of Orthis lynx: — " The smaller specimen 

 la, has three plaits in the sinus and four on the mesial lobe, with seven on each 

 side, thus : 7 f 1. In figures c and d, there is a full development of the f medial 

 plications and 10 lateral ones." The reader is requested to compare this with our 

 note on page 53 of the present volume. 



CANADIAN ORGANIC REMAINS. 



Decades I. and IV. of this important publication have just been issued by the 

 Geological Survey of Canada. We hope to notice these Decades in detail in 

 an early number of the Journal. In the mean time we can remind our readers 

 that copies can be obtained through any bookseller. 



E. J. C. 



