Geological Society. 47 



The tree had probably been introduced from Egypt by the Arabs. 



The paper and drawings were communicated by the Council of 

 the Royal Asiatic Society. 



Dec. 9. Read a paper On the plant which yields the Gum Am- 

 moniacum, by Mr. David Don, Lib. L.S. 



Although the gum Ammoniacum has held a place in the Phar- 

 macopoeia from a very early period, yet the plant itself has hitherto 

 remained wholly unknown. It proves to be a new genus, belong- 

 ing to the group of UmbellifercK, named by DeCandolle Pence- 

 danecz, differing essentially from Ferula and Opopannx in its large 

 cup-shaped epigynous disk, and in having solitary resiniferous canals. 

 The specimen was obtained, in the districts where the gum Ammo- 

 niacum is collected, by Lieut. -colonel Wright, of the Royal Engi- 

 neers on his way through Persia from India, and was by him pre- 

 sented along with other dried plants to the Linnsean Society. Every 

 part of the specimen is covered by drops of a gum, possessing all the 

 characters of gum Ammoniacum, and this circumstance alone would 

 seem sufficient to remove all doubt on the subject, but Mr. Don has 

 carefully compared it with the fruit and fragments of the inflores- 

 cence found intermixed with the gum in the shops, and he finds 

 them to accord in every respect, so that the plant may now be con- 

 sidered as fully ascertained. Dioscorides derives the name Ammo- 

 niacum from Ammon or Hammon, the Jupiter of the Libyans, whose 

 temple was situated in the desert of Cyrene, near to which the 

 plant was said to grow; but as the plant is now ascertained to come 

 from the north of Persia, and not from Africa, Mr. Don is disposed 

 to consider the name Ammoniacum or Armoniacum, as it is indif- 

 ferently written by ancient authors, as merely a corruption of Ar- 

 meniacum. We subjoin Mr. Don's essential character of the 

 genus, and some of the more important parts of the detailed de- 

 scription. 



DOREMA. Discus epigynus cyathiformis. Achenia compressa, 

 marginata: costis 3 intermediis disiinctis, filiformibus. Valleciilce uni- 

 vittatae. Commissura 4-vittata. 



Herba (Persica) robusta, facie fere Opopanacis. Folia ampla, sub- 

 bipinnata. Umbella prolifera, subracemosa. Umbellulae globosce t 

 breviter pedunculate. Flores sessiles, lanuginiimmersi! 

 The species is Dorema Ammoniacum. 



Mr. Don concludes his paper with a few observations on the plant 

 which yields the analogous gum Galbanum, which he regards as 

 constituting also a new genus allied to Siler, but differing essentially 

 in the absence of dorsal resiniferous canals to the fruit, and in the 

 commissure being furnished with two only. He proposes for the 

 plant the name of Galbanum officinale. The Bubon Galbanum of 

 Linnaeus possesses neither the smell nor taste of Galbanum, and is 

 altogether a totally different plant. 



GEOLOGICAL SOCIETY. 



Nov. 3. In consequence of the Resolutions passed at the general 

 meeting held on the 18th of last June, changing the evenings of 



ordinary 



