CHAPTER VIII 



THE FOOD OF ANIMALS— NEMERTINES AND 

 CARNIVOROUS MOLLUSCS 



Having briefly dealt with Vertebrates, we now proceed to the 

 consideration of the food and feeding habits of carnivorous Inver- 

 tebrates, beginning with Nemertines, and taking next the great 

 phylum of Mollusca. 



NEMERTINES 



These curious worm-like marine forms, which 

 scribed elsewhere as regards their structure (see 

 are purely carnivorous, preying upon all sorts 

 of creatures, both alive and dead. The mouth 

 and front part of the digestive tube are capable 

 of a large amount of dilatation, enabling com- 

 paratively large bodies to be swallowed with 

 ease. The most remarkable peculiarity of these 

 animals is the possession of a long tubular 

 "proboscis", which, when not in use, is con- 

 tained in a sheath running along the upper 

 side of the body, from which it can be shot out 

 with great rapidity through a small hole situ- 

 ated in most cases in front of the mouth, though 

 sometimes placed within it. The proboscis 

 appears to be used for seizing food, and in a 

 large number of forms its tip is provided with 

 a sharp stylet, at the base of which poison- 

 glands open (fig. 375). This is probably to 

 be regarded as a means of overpowering 

 prey. 



have been de- 

 vol. i p. 306), 



Fig. 375.— Front End of 

 Nemertine, with proboscis 

 partly protruded. Seen from 

 above (diagrammatic) 



kd. Head; pr, proboscis; 

 j/, stylet; r.si, one of the 

 two sacs containing reserve 

 stylets; p.gL, poison-gland; 

 r.m.^ retractor muscle. 



