POLLINATION OF THE BRITISH PRIMULAS. 137 
Mr. W. H. T. Tams, F.E.S., of the British Museum, who kindly measured 
the tongue-lengths of most of the species on Dr. Perkins’s list. The results 
were of much interest *. It appeared that, of nearly thirty species of moth 
of which Mr. Tams ascertained the tongue-lengths, five species only possessed 
tongues of sufficient length (say, 10 mm. or over) to reach the nectar in the 
flowers of any of the three Primulas concerned, namely :— 
Calocampa exoleta (L.) (tongue-length about 12 mm.); 
Calocampa vetusta Hub. (tongue-length about 12 mm.); 
` Phlogophora meticulosa (L.) (tongue-length about 11 mm.); 
Cucullia verbasci (L.) (tongue-length about 20 mm.) ; and 
Cucullia scrophularie Cap. (tongue-length about 20 mm.). 
All these are common species and all have (like both the Primrose and the 
Cowslip) a natural range covering the whole of the British Isles. Finally, 
one of these five species (namely, Cucullia verbasci) is the only species which 
has ever been actually observed to visit a flower of any one of the three 
Primulas concerned f. 
It is, therefore, beyond dispute that various species of moth capable of 
pollinating the flowers in question not only exist, but are common ; also that 
one of those species has been taken in the very act of visiting a flower. 
All the foregoing facts tend, I think, to show that Darwin's hypothesis, 
though as yet unproved, is probably correct. At all events, it has been 
accepted more or less definitely by I. H. Burkill, Lubbock$, E. G. High- 
field |, and other writers on the subject. 
That the Primrose must be pollinated in some places, at any rate, by 
moths solely seems clear from the fact that, on the remote island of St. Kilda, 
where the plant is  Plentiful on some of the cliffs,” Mr. Alexander H. Gibson 
asserts** that * Dutterflies, bees, wasps, and possibly ants, do not occur," 
though “ several species of moths” (which he does not name) do occur ; and 
he supposes (with, apparently, ample justification, assuming his facts to be 
correct) that, on the island, the Primrose and other flowers must be pollinated 
by these moths tt. 
The same may or may not be the case in Faroe, where, according to 
* l'or details, see Journ. of Botany, Ix. (1922), pp. 203-205. 
+ See ante, pp. 108, 128,185. — 
[ Journ. of Botany, xxxv. (1897), p. 186. 
§ ‘ Brit. Flowering Plants,’ p. 269 (1905). 
| Knowledge, xxxix. (1916), p. 113. 
€ See R. M. Barrington, in Journ. of Botany, xxiv. (1886), p. 215. 
** See Trans. Bot..Soc. of Edinb. xix. (1893), p. 156. 
++ Knuth quotes quite erroneously (‘Flower Pollination,’ iii, p. 69) this inference by 
Gibson, declaring that he attributes pollination to * flies"; and in this Knuth has misled 
at least one later English writer. 
LINN. JOURN.— BOTANY, VOL. XLVI, L 
