which yields the Gum Ammoniacum. 601 



with the gum in the shops, and I find them to agree in every 

 particular. The name applied to the plant by Dioscorides is 

 already preoccupied by another genus of Umhelliferce ; and 

 that of Pliny is scarcely unexceptionable, as originating in a 

 mistake, Metopium having been used by some ancient authors 

 to denote the Galbanum, and by others the gum Arabic tree ; 

 but most writers seem to agree in considering it the appella- 

 tion of an ointment, or some oleaginous substance, rather than 

 of a plant. To avoid any confusion, and as the plant proves to 

 be a new genus, I propose to call it Dorema, from the Greek 

 word ^o§ti[ji.u, a gift or benefit ; not that I consider the Ammo- 

 niacum plant as pre-eminently deserving that title, but the name 

 is at least a short one, and agreeable to the ear, — considerations 

 not to be overlooked in nomenclature. I shall now proceed to 

 give the essential character and a detailed description of the 

 genus. 



DOREMA. 



Syst. Linn. Pentandria Digynia. 



Ord. Nat. Umbellifer;e. Juss. Trib. vii. PEucEDANE^i. 



DeCand. 



Char. Essent. Discus epigynus cyathiformis, Achenia com- 

 pressa, marginata : costis 3 intermediis distinctis, filiformi- 

 bus. Vallecula univittatae. Commissura 4-vittata. 



Descr. Flores lanugini immersi, sessiles ! Calycis margo 5- 

 dentatus : dentibus ovatis, acutis, membranaceis, exiguis. 

 Petala 5, ovata, acumine inflexo. Stamina 6, cit6 ca- 

 duca : Jilamenta complanata, basi dilatata : antherce in- 

 cumbentes, biloculares : loculis longitudinaliter dehiscen- 

 tibus, basi solutis, parilm divergentibus. Ovaria subte- 

 retia, lineis 6 utrinqiie exarata : disco epigyno amplo, car- 



4 H 2 noso. 



