196 THE ZOOLOGIST. 



wings showing the white lining contrasted with the black head and 

 breast — in which position it might well serve as the Prussian Eagle 

 wearing the German colours and howling the " Hymn of Hate " — 

 becomes, on the other hand, much paler when feeding, the face turning 

 yellow and the feet brick-red or even flesh-colour. The sight of food 

 at a distance will cause this change to begin. Similarly I saw in 

 two Caracaras (Polyborus brasiliensis), which were from their move- 

 ments apparently courting, with thrown-back heads and reiterated 

 cries, that the face was yellow, instead of pale red, as it often is in 

 this bird, and was in some quiescent adjoining specimens. In a 

 Pileated Vulture (Necrosyrtes pileatus), however, in the Zoo some 

 time back, the bare face, livid fleshy- white ordinarily used to become 

 brilliant rose-pink, contrasting with the bluish eyelids, as the bird 

 hopped about in the scramble at feeding-time. The legs in the last 

 two birds do not change. — F. Finn. 



"gastropoda. 



Appetite of Snails for Green Material. — With regard to your 

 correspondent's interesting note on the appetite possessed by her 

 Slugs for green material, it might interest her to know that I have 

 observed the same characteristic in several specimens of Helix 

 aspersa kept for observation purposes under the same conditions as 

 those of your correspondent. I had for some time wondered over 

 the appearance of small holes in the green covering ; and I received 

 the clue from your correspondent, and watched carefully. The 

 Snails only attack the covering on nights when they have not had 

 their usual amount of food — four cabbage-leaves (young and small). 

 And they certainly do not make such quick work of it as did the 

 Slugs. During the operation, the horny " jaw " seems to play a 

 much greater part than does the actual radula ; a fact I think rather 

 curious, as the "jaw " seems actually to he projected, and the radula 

 used simply to bring the muslin against it, not for scraping. They 

 take a long time, as I watched one Snail at work for over half-an- 

 hour before he severed a single mesh. I caught one Snail engaged 

 in enlarging a hole already started, and, fearing it would escape, I 

 acted on a foolish impulse and knocked it down ; four Snails in 

 succession came up to the hole, thrust their heads out, and seemed 

 to look about them ; then, apparently finding it impossible to get 

 their shells out, with an air very humorous, inasmuch as it seemed 

 to express disappointment, they retreated. Those parts of the 

 muslin of which the colour has been altered by the deposit of mucus 



