ME. G. BENT HAM ON OBCHIDE.2E. 341 



compelled to admit them as a distinct subtribe. They are tall, 

 terrestrial plants, with plicate or strongly ribbed leaves, and are 

 usually either branched or with branched or at once axillary and 

 termiual inflorescences. Corymbis, Thou., six or seven species, is 

 widely dispersed over the tropical regions of the New as well as 

 the Old World. Not only have the Asiatic species published as 

 Hysteria, Reinw., PJiynchanthera, Blume, and Macrostyles, v. 

 Breda, proved to be strictly congeners, but the two American 

 species of Ghloidia, Lindl., show none but very slight specific 

 differences in habit or character, the whole forming a very natural 

 genus. Tropidia, Lindl., containing about five species from the 

 Indo-Malayan and South- Pacific regions, is equally well charac- 

 terized, if we include in it Cnetnidia, Lindl., Ptic7tochilus, Schau., 

 and Govindovia, Wight. 



Subtribe 3. Spib. anther. — These are all terrestrial, with a 

 creeping or short rhizome, not forming, as far as known, any under- 

 ground tubers. The flowering-stems are erect, simple, with mem- 

 branous leaves or very rarely leafless, and a simple terminal 

 raceme sometimes condensed into a spike. The rostellum is 

 terminal and erect or inclined forward, the anther behind the 

 rostellum and parallel to it, the pollen-masses after dehiscence 

 either suspended from or attached to the gland of the rostellum, 

 or affixed to the end of a stipes descending from that gland. The 

 thirty-five genera comprised in the subtribe may be distributed 

 into two series, well indicated by Blume, but whose character may, 

 in the case of some genera, require further investigation on living 

 specimens, for the j)recise nature of the pollen is often very diffi- 

 cult to ascertain in the dried state. 



Series 1. Genera either tropical American or extratropical in 

 both worlds, with the exception of a very few species of Spiranthes 

 itself in the tropical regions of the Old World, the pollen almost 

 always finely granular or mealy. They include eight genera with 

 the labellum superior — Altensteinia, Pterichis, Cranicliis, Pres- 

 cottia, Wullsehlaegelia, Pseudocentrum, Gomphichis, and Steno- 

 ptera, all tropical American ; and six with the labellum inferior or 

 pendulous — Neottia, Listera, Spiranthes, Ponthieva, BasTcervilla, 

 and Pelexia, some of which have a more general geographical dis- 

 tribution. 



Altensteinia, H. B. & K., about twelve species, should include 

 Aa and Myrosmodes, Eeichb. f., as appears to be admitted by the 

 author (Xen. Orch. iii. 18). Pterichis, Lindl., including Acrcea 



