236 MR. H. BOLUS ON SOME CAPE ORCHIDS. 
Disa ; though he remarks that, “ generally the distinction between 
Disa and its nearest allies can scarcely be settled without a study 
of the living plants." I venture to suggest the restoration of Her- 
schelia, distinguished from Disa by (1) its bilobed stigma, (2) its 
tripartite rostellum, and (3) pollinia generally united to a single 
gland. To Herschelia ccelestis, Lindl., hitherto the only species, 
should be added H. barbata, mihi (Disa barbata, Sw.). These two 
plants are similar in habit; and though they have also a certain 
resemblance in leaves &c. to the Disc of the section|Zrichochilia, 
yet these latter have always a clawed labellum dilated at the 
apex; while in Herschelia the labellum is sessile. 
PENTHEA, Lindl, 
Lindley has separated the genus Penthea from Disa from the 
fact of the intermediate sepal having no spur. After the generic 
description, he says briefly :—“ Disa differt sepalo altero ecal- 
carato.” 
In habit there is scarcely any difference ; and the genera overlap 
ın such plants as Disa secunda, Sw., described as having its inter- 
mediate sepal “dorsi saccato,” and Penthea atricapilla, Harv., 
where it is described as “galea lineari-oblonga acuta basi plana 
apice cucullata.” Harvey remarks (Lond. Journ. Bot. i. p. 17):— 
“ The character of wanting a spur is only absolutely true in 
P. patens; in P. melaleuca, obtusa, and filiformis [sic] the galea is 
either saccate or umbonate.” To this he might have added that 
in P. atricapilla it is cucullate. Elsewhere (Thesaur. Cap. p. 54), 
speaking of Disa melaleuca, Thunb., he observes :—“ In Disa the 
spur varies extremely; and in D. secunda is nearly as obsolete as 
in the present plant.” 
The only members of the group which have a distinct and pecu- 
liar facies are P. melaleuca and the closely allied P. atricapilla. 
But the different appearance of these is due to the abbreviated, 
somewhat corymbose inflorescence, to the arrangement of the 
colours of the flower and the relative position of its parts, rather 
than to any structural distinctions. 
On these grounds I cannot think that Penthea should stand. 
As Mr. Bentham points out (loc. cit.), the sections of Disa pro- 
posed by Lindley are very unsatisfactorily characterized; in any 
new arrangement Penthea obtusa, P. filicornis, and P. reflexa 
would be ranged with Disa secunda; while P. melaleuca and 
P, atricapilla would form a very distinct section. 
