240 MR. G. BENT HAM ON EUPHORBTACKJB. 



and after him Endlicher, gave the tribual name Hippomaneae. 

 Mueller adopted the name, but extended the tribe so as to con- 

 tain a large number of very dissimilar genera, connected together 

 by the sole character of having the male calyx either imbricate or 

 not strictly valvate, distinguishing the true Hippomanese as a 

 eubtribe Euhippomanece. Baillon, in his ' Histoire des Plantes,' 

 returned to the old limits, but replaced Bartling's name by that 

 of Excoecariece, for which change he does not give any reason ; and 

 the character he gives of the series (Hist. PL v. 15), though 

 applicable to many species, has far too many exceptions to be 

 practically useful. Very precise characters it is indeed impossible 

 to give. The principal one consists in the great reduction of the 

 male calyx, leaving the anthers exposed in an early stage, and 

 either cupular with a sinuate margin or with broad imbricate 

 lobes, or reduced to three distinct scale-like sepals, or entirely 

 wanting, and never valvate as in Acalyphere. The male flowers 

 are usually in catkin-like spikes or in heads ; the bracts sub- 

 tending the flowers have usually, but not always, a large gland 

 on each side at the base ; the styles in a few genera show the 

 large fleshy column of Plukenetiese, but are very variable. The 

 normal genera, with the single flowers or small clusters subtended 

 by small bracts usually biglandular, may be distributed into two 

 groups — the first with indefinite stamens usually more than six, 

 the second with one, two, or rarely three or more stamens in the 

 male flowers, and the calyx often more reduced than in the first ; 

 to these are added three genera with very abnormal bracts. 



The first group includes five genera: — 1. Mabea, a very natural 

 and well defined tropical American genus of about 16 species, 

 sometimes rather difficult to distinguish from each other ; the 

 climbing habit and columnar style bring the genus very near 

 to Plukenetieae. 2. Homalanthus, an old and well-established 

 genus of 7 or 8 species from the Malayan archipelago, tropical 

 Australia, and the South-Pacific islands. I have already shown 

 the impropriety of changing the name to Carumbium ; and in the 

 1 Plora Australiensis ' I have given my reasons for following 

 Baillon in restoring to the genus Mueller's Wartmannia. 3. Pi- 

 meleodendron, 2 or 3 species from the Malayan archipelago, 

 united by Baillon with Homalanthus on account of the similarly 

 flattened calyx ; but the calyx is not quite the same, and the foliage, 

 inflorescence, and anthers very different. The typical species forms 

 in the ■ Prodromus ■ a section of Homalanthus (Carumbium) ; but 



