28 



BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



In most nemerteans, however, the proboscis can be everted so 

 that it extends for a consideral)le distance beyond the tip of the 

 snout. When everted the thick inner ei)itlieliuni with its extremely 

 viscid secretions comes to lie externally, where it can be brought 

 into contact with either the prey or the enemies of the worm. 



In the forms provided mth a Avell developed stylet the body of 

 the prey or enemy can be pierced by this, and at the same time held 

 firmly by the exti-emely tenacious secretion of the anterior proboscis 

 chamber. The secretion of the posterior chamber very probably 

 aids in paralyzing the victim. 



In the forms without stylets the pi-oboscis can hold any small 

 object, such as another worm or crustacean, very fii-mly by coil- 



^^^^ 



YiG. S.—Carcinonemertes epialti. Horizontal section of proboscis lying in natural 

 position between brain lobes (br), and showing posterior chamber at right 

 angles to general axis of proboscis. 



ing: about it and secreting its tenacious mucus. Various sorts of 

 stinging hairs, or nematocysts, aid in the capture of the prey in 

 certain species, as described below. 



In many forms the pi-oboscis further aids the worm in burrowing. 

 C.B.Wilson (-.00, p. 105) describes a specimen of Cerehratulus 

 lacteus in the process of burrowing as everting its proboscis for a 

 distance of six or eight inches into the mud in advance of the head 

 of the worm. 



