gangue, and much larger than these. They are religiously 

 esteemed on account of the resemblance of the black part 

 to a cross, and are sold by the monks as of great use to the 

 possessor, generally somewhat mutilated to humour the 

 appearance of the cross, and to fit them for wearing, as 

 preservatives from all evils. Mr. Humphrys has a specimen 

 of this last sort about three quarters of an inch broad at top, 

 and nearlv resembling- ours. 



Mr. Hailstone promised to lend me that in Dr. Wood- 

 ward's collection at Cambridge, if different or better than 

 the one figured ; and as I have not received it, we may con- 

 clude it is nearly the same. 



As far as we have seen, it is crystallized in slightly rhom- 

 boidal four-sided prisms of about 8 5° and 95°, according to 

 De PIsle. The laminae seem parallel to the faces of the 

 column, and there appears by the construction and meeting 

 of the laminae that there may be a diagonal division. Frac- 

 ture fine, earthy, approaching to splintery. According to 

 Haiiy, it appears that the integrant molecule is the te- 

 traedron. 



I hope we may meet with this fossil in greater perfection 

 one day in Great Britain, so that I may be able to give a 

 better account of it. I have something so nearly resembling 

 it that T am apt to think they are the same, with an almost 

 entire black centre, and merely a whiter pearly covering. 

 The black is generally supposed to be like the shale or 

 substance the crystals are enclosed in, so that the whiter 

 part is chiefiv spoken of; and it is very curious that they are 

 so governed by a peculiar modification as to conjoin in such 

 a manner as to envelope each other, yet retaining the 

 rhomboidal form. 



Spec. Grav. 2'9444. 



As we have seen no analysis, we could not determine its 

 systematic name or place ; but we hope to attain more 

 knowledge of it at some future period. 



