344 THE FERTILISATION OF FLOWERS. [PART IL 
cp. and s., very freq. ; (9) Megachile centuncularis, F.. ¢, s. ; (b) Sphegide : 
(10) Lindenius albilabris, F.. B. Diptera—(a) Syrphide : (11) Eristalis tenax, 
L., s and f.p.; (12) Volucella bombylans, L., do. ; (13) Syrphus tricinetu 
Fallen, f.p.; (6) Conopide : (14) Sicus ferrugineus, L., s. C. Lepidoptera— 
(a) Rhopalocera: (15) Pieris brassicae, L. ; (16) P. rape, L. ; (17) P. napi, L. ; 
(18) Hesperius silvanus, Esp. ; (19) Satyrus Janira, L.; (5) Noctue : (20) 
Plusia gamma, L., all rather freq.,s. D, Coleoptera—(a) Elateride: (21) 
Agriotes ustulatus, Schaller (Sid.).; (6) Cerambycidw: (22) Strangalia 
melanura, L, (Sld.), ab. See also No. 590, 111., and No. 609. 
Cnicus palustris and C. arvensis are gynodicecious according to 
Darwin (167). ‘a 
Cnicus acaulis, All., is visited by humble-bees and by Lepi- 
doptera (590, 609). | 
Cnicus spinosissimus, Scop.—The tube of the corolla is 8 
9 mm., the throat 4 to 5 mm. long. The insect-visitors are very 
numerous and various (609). ) | a? 
254. CNICUS HETEROPHYLLUS, All.—Several hundred florets 
unite to form a capitulum (I have counted 259). The tube is 
15 mm., the throat 8 mm. long. I have seen the flower visited by 
Bombus mesomelas, 9 (18 to 20) (609). 
255. ONOPoRDUM ACANTHIUM, L.—In each floret the honey 
rises in the tube, which is 10 to 12 mm. long, up to the cylindrical 
somewhat swollen throat, which is 3 to 4 mm. long, and which 
divides above into five linear segments, 6 to 8 mm. long; these 
segments do not diverge, but are continued straight upwards from 
the throat of the corolla. The length of the tube of the corolla 
in this plant, and in most other Cynarez, has no influence on the — 
accessibility of the honey, since the latter rises up into the throat ;_ 
it is due only to the development of the involucre, which gives 
effectual protection to the buds by completely surrounding them — 
in the form of a deep cup; the long tubes also serve to increase — 
the conspicuousness of the flower, as they bend more and more — 
outwards the nearer they are to the margin. The branches of 
the style are 3 to 4 mm. long; they seem never to diverge in — 
Onopordum, but remain closely appressed. They bear on thei 
outer edges rows of stigmatic papillae, which in the second (female) — 
stage of the flower turn more outwards and expose themselves to 
the touch of insect-visitors. One millimetre below its division 
into two branches, the style bears a ring of short hairs, which 
pomt obliquely upwards and are long enough to sweep the an-_ 
ther-cylinder (} mm. wide; 8 to 10 mm. long) clear of pollen. 
