Arrian and Indian Aromatic Plants 109 



tracing Sao hirsuta from its embryonic condition of a simple 

 disc-like body through twenty stages to a fully formed 

 trilobite an important discovery, for it not only illustrated 

 the life-history of that crustacean, but also reduced the 

 number of so-called species ; for, in a recently published 

 work on Bohemian trilobites, M. Corda had made ten genera 

 and eighteen species out of a part only of these stages in 

 the development of Sao hirsuta. 



Professor E. Forbes said that, as a lady had found on 

 trial, sea-water could be kept in a healthy condition for 

 animal life by pouring part of it backwards and forwards 

 through the air. 



Dr. Royle then read a letter from Dr. Hooker referring 

 to Arrian's account of plants found by Alexander's army 

 in the deserts of the Gadrosi. 1 These are (i) trees, abundant 

 and reaching a large size, which exude a gum like myrrh 

 the googal balsam tree ; (2) the salt-marsh trees with 

 thick laurel-like leaves and fragrant white flowers ; this 

 suits Aegiceras magnum ; (3) one with a thorny stem and 

 acrid juice, Euphorbia narcifolia. These three cannot be 

 mistaken, and are found within twenty miles of Karrachee. 2 

 The odoriferous herb (vapSov pi^a) is the only plant 

 difficult to identify, for there are two or three herbaceous 

 plants on the rocks in Scinde called wild nard. He thought 

 the ' root of nard ' collected by the Phoenicians must have 

 been that of the reed-like grass generally named Calamus 

 aromaticus, found in dry hot parts of India, the distilled oil 

 of which is commonly called oil of spikenard. 3 



Bohemia, of which he formed an unrivalled collection, described in his 

 Systeme Silurien de la Boheme, 22 volumes of which had been published 

 before his death. (See Geol. Mag. 1883, p. 528.) 



1 See Arrian, History of Alexander's Expedition, book vi. ch. xxii. He 

 makes the statement on the authority of Aristobulus. The army was 

 returning. 



2 Dr. Hooker did not personally vdsit this part of North-western India, 

 but probably obtained the information about its flora either at the Botanic 

 Gardens of Calcutta or from Dr. Thomson, with whom he spent about 

 nine months in exploring the Khasia mountains. 



3 Arrian states that they gathered good store of the roots, and that the 

 plants, when trodden under foot, perfumed the air. 



