[ 503 ] XXIX. Descriptions of Indian Gentianeae. By David Don, Esq., Libr. L.S., Prof. Bot. King's Coll. Lond. Read November 3rd and 17 th, 1835. Among the numerous families which compose the class of Dicotyledonous plants there is, perhaps, none so equally and generally distributed over the surface of the globe as the Gentiunece, for they are found dispersed throughout the greater part of both hemispheres ; and this observation applies not to the entire family only, but likewise to many of the smaller groups, as may be seen by consulting the table which precedes the descriptive part of this paper. In comparing the Floras of different countries, we shall find that what has been just stated with respect to their equal distribution is fully borne out by facts, at least in the Northern hemisphere, whose vegetable riches have been more completely investigated, and that they form about the proportion of -gVth of the phaenogamous vegetation. In the Swiss Flora, which comprises 2000 phsenogamous plants, 26 are of this family; in the Siberian Flora, of 170O phaenogamous plants, 21 are Gentianeoe; in that of the Caucasus and Crimea, in 2000 there are 20 ; in Peru and Quito, the phaenogamous plants of which may be estimated at 4500, there are 43 Gentianeoe ; and in the North Ame-rican Flora there are 55 out of 4081 phaenogamous plants. By the indefatigable researches of Dr. Wallich and Dr. Royle, the number of species of this family belonging to the Indian Flora has been more than doubled, and they now amount to about 50. Of the 14 genera into which they have been distributed, Canscora, Exacum, Slevogtia, Crawfurdia, Ophelia, and Agathotes are exclusively Indian, and the remaining 7 are common also to the European and Northern Asiatic Floras. Of these 50 species, 34 belong to the Alpine Flora, which in 3500, the number at which the phaenogamous plants of the Flora of Northern India may be estimated, will give a larger pro-portion than that above mentioned.
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