FERTILIZATION OF SPRING FLOWERS ON THE YORKSHIRE COAST, 141 



species-visits. In the same way it will be seen that the mid-tongued 

 bees visit mostly flowers with more accessible honey ; excluding 

 Class F from consideration by reason of the insufficiency of the 

 facts to hand, we find them making 10 per cent, of the visitants 

 to Class B, 8-7 to Class B', 7-2 to Class AB, and 6-6 to Class A. 

 The short-tongued Hymenoptera visit most freely Class AB. Thus 

 do these three divisions of the Hymenoptera make a series. The 

 Lepidoptera are mostly found on the higher, if not the highest types, 

 while the mid-tongued flies associate with the mid-tongued bees. 

 The short-tongued flies, absent on Class F, form 21-9 per cent, of 

 the species-visits to Class H, 33-3 to Class Po, 37-9 to Class B, 

 43-3 to Class AB, 43-5 to Class B', 50-0 to Class W, and to Class A, 

 the simplest which affords them honey, 56-0 per cent. And the 

 Coleoptera and Thysanoptera, which, by reason of their small 

 size, can creep into flowers, are found most abundantly in the 

 highest types, where food and shelter are obtained to the greatest 

 extent. The law that the higher types of flower and the higher 

 types of insect are mutually dependent has been so well established 

 by continental observers that we may pass on without further com- 

 ment to the consideration of the distribution of the individuals. 



Table III. — Distribution of Individuals visiting among the 

 Classes of Flowers. 



Here we enter almost new ground. Table III. expresses the 

 number of individuals seen visiting flowers of the different types, 

 and includes the meagre observations of '94, while Table IV. ex- 

 presses the same calculated in percentages. We will compare the 

 result. 



In Table IV., the lowest hne, which gives the percentages of 

 the whole of the flower-visiting insects observed, may be taken as 

 a standard of comparison. The more widely any of the percentages 

 given in the lines above differ from them, the more do the insects 

 under consideration seek or avoid that class of flowers ; thus the 

 Class B attracts thrice its share of the long-tongued bees, Class AB 

 twice its share of mid-tongued bees, and Class B' only one-third of 

 its share of short-tongued Hymenoptera. Considering next the 

 most numerous insects — Diptera— it is noted that Class A attracted 

 more than its share of the short-tongued flies, and less than its 



