96 FERTILIZATION OF SPRING FLOWERS ON THE YORKSHIRE COAST. 



and short-tongned Diptera ; C. = Coleoptera ; Hem. = Hemiptera; 

 T. = Thysanoptera. sh. = sucking honey; fp. = feeding on pollen; 

 cp. = collecting pollen as bees do for their young ; seeking h. = 

 seeking honey, but not obtaining it. '94, '95, '96 give the years in 

 which the observations were made. Square brackets [ ] are used 

 to enclose the names of species which came under observation, but 

 do not truly belong to the early spring flora. 



Distribution of Insect-visitors. 



All the plants observed in bloom during the periods of observation 

 will be mentioned here under their biological classes ; those whose 

 names are printed in small capitals (without an asterisk) are 

 flowers which — using a term foresters employ in the same sense — 

 — may be called "dominant" or "ruling" species; those in 

 small capitals preceded by an asterisk may be considered as 

 "subdominant" or "conditionally ruling"; while species whose 

 names are printed in italics are "dependent." The keenest com- 

 petition is between species of the same class, and the dependent 

 Draha verna competes with the subdominant Cochlearia ojpcinalis 

 and the dominant Itananeulits Ficaria. In a case like this, supposing 

 other things {e. (j. amount and accessibility of honey, attractiveness 

 in scent and colour, &c.) equal, the common species is a large host 

 scarcely harassed by the single regiment on its flank ; while the 

 scarce species is this single regiment, in constant danger of total 

 annihilation should the struggle become acute. 



■ot>^ 



Class I. ( W.) Wind-fertilized flowers. 



*Mercurialis perennis L. — No visitors. 

 *Ulmus cabipestris Sm. — No visitors. 

 CoRYLUs avellana L. — Dm. : Melanostoma quadrimaculatum 

 Verrall, «? and J , fp., '95. 



Alnus glutinosa L.— No visitors. 



Popuim nigra L. — Ds. : Calliphora cognata Mg., seeking h. on 

 S flowers, once, '96. 



Empetnoii nigrum L. — No visitors. 

 Poa annua L. — No visitors. 

 [Plantago lanceolata L. Luznla campestris DC. — No visitors.] 



Class II. (Po.) Flowers offering pollen only to their guests. 



*Anemone nemorosa L. — HI.: Bombus terrestris L., '94, '96. 

 Dm. : Melanostoma quadrimaculatum Verrall, fp., '95. Ds. : 

 Scatophaga stercoraria L., fp. and seeking h., '95, '96 ; Antho- 

 myia sp., fp., '95, '96. Hem. : Anthocoris sp., seeking h., '96. 

 T. : Thrips sp., ? seeking h., '96. 



Alcheiiulla (trvensis Lam. — No visitors. 



Class III. (A.) Flowers with freely-exposed honey. 

 '■■Chrysosplenium oi'PosiTii'OLiuM L. — Hs. : a small ichneumon, 

 '95. Dm. : Melanostoma quadrimaculatum Verrall, '95. Ds. : 

 Sepsis nigripes Mg., '95 ; Chironoraus ? 2 sp., 95 ; Sciara sp., 95 ; 



