Robertson — Flowers and Insects'— Labiate. 111 
essary, or if they should become extinct, or rare, or should be 
drawn away by the competition of other flowers. The — 
abundance of pollen-visitors is a result of the exposure of the 
anthers so that bees can lund upon them or in a position con- 
venient for reaching them. I think that Verbascum has 
become a synacmic pollen-flower as a result of exposing its 
anthers in such a way that they were sought so abundantly by 
pollen-insects that the nectar and the insects attracted by it 
became of no importance. To this third set of insects, in 
which Ceratina dupla (13) must be included, belong the 
following :— 
(16) Calliopsis parvus Rob. 9; (17) Augochlora pura Say Q, ab.; (18) 
Halictus 4-maculatus Rob. 9; (19) H. pectoralis Sm. Q; (20) H. coriaceus 
Sm. 9; (21) d. forbesii Rob. 9; (22) H. confusus Sm., Q, all c. p.; (23) 
Prosopis affinis Sm. <j’, 
Finally, the flowers are perforated by Odynerus forami- 
natus Sauss., which being unable to obtain the nectar in a 
legitimate way, reaches it by cutting holes in the tube. 
Monarda fistulosa * L.—The plant is very common, often 
growing in large patches along roadsides. It resembles the 
preceding, but is taller and much branched, the branches ter- _ 
minated by large heads, which rise to nearly the same Jevel and 
render the plant quite conspicuous. The heads are smaller 
than in M@. Bradburiana, about 45 mm. across, the flowers 
being of a uniform rose color. : 
The corolla measures about 30 mm. to the tip of the upper 
lip, the lower lip being about 12 mm. The upper lip is 
narrow, is continued directly upwards in line with the axis of 
the tube and seems to be of little or no value as a protection 
to the anthers and stigma, since these parts surpass its tip. 
The anthers and stigma stand 12 mm. distant from the lower 
lip and are hardly bent towards it, so that only the largest 
bees are likely to touch them when landing upon the lip. 
On account of the erect position of the flowers, the expos- 
ure of the anthers and stigma, and the crowding of the flowers 
in an almost flat-topped cluster, the irregularity of the corolla 
* See Foerste: Bot. Gaz. XIII, 154. 
