Genth.] 



34 



[March 18, 



Considering the crystals as a combination of a macrodome d with a 

 brachydome o, the approximately measured angles d : d in axis c = 101° 

 30' and 102° 30' and o : o in axis a = 103O 30', 104O 3G' and 105° 30', a 

 form which is very close to that of anglesite, if we compare d with ^ Poo 

 (lOlo 13') and o with Poo (104° 24'). 



Fig. 9. 



Prof, vom Rath is opposed to this view ; he would look upon it favor- 

 ably if only isolated crystals had been observed, but would consider it 

 very strange to find the skeleton-like formation and the reticulated ar- 

 rangement of the aggregations in anglesite. He suggests that the primitive 

 mineral might have been reticulated galenite, and he has been supported 

 in this view by the late Prof. Websky, Prof. Descloizeaux and Dr. Hintze. 

 Considering galenite as the primitive mineral, the apparently rhombic 

 forms of these pseudomorphs would be distortions or irregular hemihe- 

 dries of isometric forms, as it is well known how frequently galenite oc- 

 curs in forms which have not the habitus of isometric crystals. 



However, he was not able to reduce these oblongoctachedrons to nor- 

 mal planes of galenite, and notwithstanding the important opinions sus- 

 taining his views, Prof, vom Rath does not feel satisfied and expresses his 

 manifest doubts by suggesting that, these forms might be pseudomorphs 

 after a yet unknown rhombic mineral, having a tendency to occur in 

 skeleton-like aggregations. 



I have examined the reticulated galenite specimens in Mr. Clarence S. 

 Bement's magnificent cabinet, but could not satisfy myself that the pseu- 

 domorphs under consideration could have resulted from such forms of 

 galenite. 



Reticulated galenite is of a rather rare occurrence, and such forms 

 would not be known, if the few localities where it has been found would 

 not furnish it. That anglesite has not been observed in such forms before, 

 does not prove the non-existence of the same. 



A suite of these pseudomorphous forms was sent by me to the Imperial 



