INSULAR FLORAS. 457 



relation to the distribution of generic types. Foremost 

 among these are the Baobabs (Adansonia), of which, 

 according to Baillon (32), there are several species in the 

 island, so that the solitary tropical African species and the 

 remote Australian one may be regarded as outliers of a 

 genus having its greatest concentration in Madagascar. 

 There is evidence, too, that the insular species sometimes 

 attain very large dimensions ; a trunk with a diameter of 

 twenty-two feet at six feet from the ground being on record. 

 The characteristic Kigelia (Bignoniaceae), on the other hand, 

 is represented by one species in Madagascar and several 

 in Africa. Hibbcrtia Aubertii (Dilleniaceae) is a solitary 

 outlier of an Australian genus numbering upwards of fifty 

 species, with three or four others in Polynesia. With regard 

 to the phyllodineous Acacia Jicterophylta, which is an 

 Australian type, and which is generally considered to be 

 indigenous in Bourbon and Mauritius, Baron enumerates 

 it among the introduced cultivated plants in Madagascar ; 

 and Mr. J. G. Baker informs me that he is now convinced 

 that the form he described as a new species under the 

 name of xiphophylla is only a cultivated state of A. 

 heteropJiylla. It is possible that there is still something 

 more to be learnt about this species, as it is hardly dis- 

 tinguishable from the Hawaiian A. Koa. Nepenthes is a 

 noteworthy essentially Asiatic genus represented in Mada- 

 gascar by one species, but not reaching Africa. The 

 discovery in Madagascar of a species of the parasitic genus 

 Cytinus is of more than ordinary interest, because the 

 present distribution and relative rarity of plants of this 

 class (and also saprophytes) indicate their gradual extinction. 

 They seem to have disappeared from large areas, conse- 

 quent on the early destruction of forests, and to have 

 survived in remotely distant localities, where the conditions 

 remained favourable to their existence. Mr. E. G. Baker 

 describes (33) Cytinus Baroni as differing from all the 

 other species of the genus in growing on the trunks of 

 trees, instead of on the roots of other plants. Cytinus is 

 closely related to the gigantic Rafflesia that grows on the 

 roots of vines in the Malay Archipelago. Of the four 



