EUPHOEBIUM. 389 



dusty particles from annoying them, as they produce incessant 

 sneezing. 



The history of the Euphorbium as given in the ' Pharmaco- 

 graphia' is, that it was known to both Dioscorides and Pliny as 

 a native of the Atlas, and was named in honour of Euphorbus, 

 physician to the learned King Juba II. of Mauritania, himself 

 the author of treatises on Opium and Euphorbium. 



The prevalence of caotoid Euphorbice in Marocco, of which 

 there are three species in the southern districts, Ls a similar 

 instance to that of the Argan, of tropical forms advancing far 

 noi-th in the extreme west of the old world ; and as the Argan 

 has its nearest ally in Madeira, so have the Maroccan Euphor- 

 biums close congeners in the Canary Islands. All these belong 

 to the section Diacanthium of Boissier, of which the other 

 species are Abyssinian, Arabian, Indian, and South African. 



Gum Euphorbium was extensively used by early practitioners 

 as an emetic and purgative, and was exported in large quantities ; 

 now, however, the trade in it is rapidly declining, and we were 

 informed that it is chiefly used in veterinary practice, and as an 

 ingredient in a paint for the preservation of ships' bottoms. 



Euphorbia resinifera is in cultivation at Kew, where speci- 

 mens may be seen both in the Succulent-plant House and 

 Economic-plant House. 



The Arar, Thuja or Gum Sandrac Tree. 



CaUitris quadrivalvis. — Ventenat, Nov. Gen. Decad. 10 ; 



Eichard, Conif. 46, t. 8, f. 1 ; Endlich, Synops. Conif. 41 ; Par- 



latore, in DC. Prod. xvi. pars 2, 452 ; Ball, in Journ. Linn. 



See. Bot. xvi., 670. 

 Thuja articulata. — Shaw's ' Travels in Barbary,' 462, with a 



plate ; Vahl, Symb. ii. 96, t. 48 ; Desf. Flor. Atlant. ii. 353, t. 



252. 

 Frenda Fontanesii. — Mirbel, in Mem. Mus. xiii. 74. 



This tree is a native of the mountains of North Africa, 

 from the Atlantic to Eastern Algeria ; but we are not aware 

 whether its eastern limit has ever been accurately determined. 

 It has no congener, its nearest ally being a South African genus of 

 Cypresses (Widdringtonia), of which several species are recorded 



