NEREIS MARGARITACEA. 319 



running down the back ; the whole surface is finely 

 iridescent. Two black incurving jaws are seen within 

 the orifice of the proboscis, their extremities project- 

 ing just beyond it. 



This creature constructs a very thin transparent 

 silky tube, composed of a material, that, apparently, 

 exudes from the whole surface of its body, wherein it 

 keeps itself concealed, except the head, which remains 

 exposed, and is commonly found waving from side to 

 side. The tube is often strengthened by having sand 

 incorporated with it, where this material is accessible ; 

 if not, it remains quite transparent. It is always 

 formed of sufficient width to allow of the animal's 

 reversing its position within. 



The Nereis fulgens is a littoral species ; it retreats 

 from the light, lurking under stones or in clefts. 

 Fine specimens may frequently be found by raising 

 shelving portions of rock near low water. 



NEREIS (NEPHTHYS) MARGARITACEA. 



The NEREIS (NEPHTHYS) MARGARITACEA, the Pearly 

 Nereis, is a magnificent species, sometimes measuring 

 ten inches in length, and consisting, when full-grown, 

 of upwards of a hundred and forty segments, each 

 provided with a complete set of locomotive organs. 

 Two short stumps are situated on the head, and a 

 proboscis of extraordinary dimensions is occasionally 

 darted forth. Sometimes a black speck is seen in 

 front ; but it is neither constant, nor are eyes visible. 

 The shape of the proboscis varies considerably, but it 

 is generally somewhat barrel- shaped, and about three- 



