MANNER OF FEEDING IN TESTACELLA SCUTULUM. 287 



The movements described above have the following effect on 

 the teeth : — The protrusion of the basal cartilage tightens the 

 radula, especially as it passes over the edges of its support, and 

 as these approximate, the teeth on the outside stand more erect, 

 and those on the edge bend inwards and overhang their com- 

 panions in the hollow, with their barbs pointing to those of the 

 other side (fig. 3 a). Thus an action is effected resembling that 

 of the steel jaws of a spring-trap. 



If the body of an earthworm be within reach of any of the 

 barbs, it is pierced and held, but when the two series along the 

 edges of the radula grip it, the body of the worm gets forced into 

 the hollow, and caught on the more hidden points. In some 

 instances where the worm was seized by the middle it forced 

 itself away, but when, as was usually the case, the radula closed 

 on its anterior end, its fate was sealed (figs. 4 and 4 a). The 

 radula and its cartilage are next withdrawn into the bod}', as far 

 as its contracted state will allow, and the Testacella very gradually 

 extends itself, giving more room inside, and crawling on to its 

 prey literally envelops it. The worm, if small compared with 

 the slug, disappears in a comparatively short space of time. 



There does not seem to be any reason for supposing that 

 Testacella only feeds at night, although, as earthworms seldom 

 come above ground before daylight disappears, the slugs usually 

 remain underground until that time. The experiments referred 

 to above were all made in the daytime, and one morning many 

 years ago, the writer saw a large yellow specimen, in a garden 

 at Hampstead Heath, which had managed to secure a fine lob- 

 worm. 



Putting on one side such manifest elaborations as the 

 crouching and springing described by Jeffreys, it seems very 

 questionable whether Testacella stalks its prey, or even takes any 

 direct notice of it at all until contact takes place. It is probable 

 that its so-called agility consists merely of the strikingly rapid, 

 but more or less automatic, protrusion of the radula, and that its 

 indifference with regard to the worm's proximity that has been 

 insisted upon, is a matter of necessity, and not invention. 



It has already been remarked that some worms escaped when 

 caught by the middle, while those seized so near to the anterior 

 end that this was dragged in front of the mouth were ultimately 

 swallowed* The first observer quoted expressly mentions the 



