11 



DESCRIPTION OF A NEW SPECIES OF ORCHID. 



By R. S. Rogers, M.A., M.D. 



[Read November 5, 1907.] 



Prasophyllum occidentale, sp. nov. 



Plant. — A somewhat dwarfed species, varying from 5 to 

 8 in. in height ; the iistula in the sheath placed high up, 

 sometimes immediately below the spike. Leaf-lamina greatly 

 exceeding the spike, extending in my smallest specimen 4J 

 in. beyond the fistula, and in my tallest 6 in. beyond this 

 point. The spike not crowded, consisting of from ten to 

 fourteen green flowers. 



Flowers. — Lateral sepals about 3 lines long, slightly bi- 

 dentate, united except in their distal fourth. Dorsal sejDal 

 somewhat shorter (2 J lines), erect, acuminate, concave. Late- 

 ral petals narrow-lanceolate, very slightly shorter than dorsal 

 sepal. 



Lahellinn. — Sessile, about 2 lines long, reflexed about the 

 middle, tip acuminate ; membranous portion fairly wide and 

 slightly crenulated, callous part continues a short distance 

 beyond the bend : does not protrude between the free tips of 

 sepals. 



Column.— Middle lobe quadrangular. Lateral appen- 

 dages about same height as rostellum ; unequally lobed, the 

 smaller one being given off about middle of appendage. Stig- 

 matic plate speckled in my specimens. 



I found this orchid growing close to the shore at Streaky 

 Bay on September 26, 1907. Only four specimens were col- 

 lected, and three of these were seeding, so that it should be 

 looked for at the beginning of the month. 



It bears a superficial resemblance to the Western Aus- 

 tralian form, P. macrostachyurn , from which, however, it may 

 be distinguished by its relatively long and narrow petals, by 

 the extent to which its lateral sepals cohere, and by tlie 

 great length of its leaf -lamina. 



There is no recorded member of the genus in this State 

 with which it is likely to be confused, unless it be P. fuscum. 

 In this species the lateral sepals are free, whereas in the new 

 form they are connate, a feature which at once makes the 

 diagnosis easy. 



