i8o 



POSITION OF THE EYES 



curious points came out in his tal)le of results. Arnalia gagates 

 appears to be surprisingly omnivorous, for out of 197 kinds of 

 food it ate all but 25 ; Avion atcr came next, eating all but 40. 

 Limax arhorio/i, on the other hand, was dainty to a fault, eating- 

 only seven kinds of food, and actually refusing Swedes, which every 

 other species took with some avidity. Certain food was rejected 

 by all alike, e.g. London Pride, Dog Eose, Beech and Chestnut 

 leaves. Spruce Fir, Conniion Eush, Liverwort, and Lichens : while 

 all, or nearly all, ate greedily of Potatoes, Turnips, Swedes, 

 Lettuces, Leeks, Strawberries, JBoleUis edulis, and common 

 grasses. Few of our common weeds or hedgerow flowers were 

 altogether rejected. Avion and Limax were decidedly less 

 particular in tlieir food than Helix, nearly all of them eating- 

 earth-worms and puff-balls, which no Helix would touch. Avion 

 ■ atev and Limax niaximus ate the slime off one another, and 

 portions of skin. Cyclostoma elegans and Hyalinia nitida 

 preferred moist dead leaves to anything else. 



II. /Sup- 

 position of Eyes. — In the majority of the head-bearing- 

 ]\IollusL'a the eyes are two in number, antl are placed on, or in 

 the immediate neighbourhood of the head. Sometimes they are 

 carried on projecting tentacles or ' onnuatophores,' whicli are 

 either simple (as in Prosobranchiata) or capable of retraction 



Fig. 86. — A, Livinaea peregra Mtill. ; e, e, eyes ; t, i, tentacles : B, Helix nemoralis 

 Miill. ; e, e, eyes ; t, t, tentacles ; p-o, pulmonary orifice. 



like the fingers of a glove {Helix, etc.). Sometimes, as in a large 

 nundjer of the marine Gasteropoda, the eyes are at the outer base 

 of the ceplialic tentacles, or are mounted on the tentacles them- 

 selves, but never at the tip (compare Fig. 60, p. 153 and Fig. 98, 



