48 ART. 8. 1. IKEDA : THEEE NEW AND 



species allied to, but quite distinct from, the one just mentioned. 

 Th. elegans inhabits the same shallow and muddy ground as Th. 

 tœnioides, in the inlet of Moroiso, close to the Misaki Marine 

 Laboratory. It lives in deep, vertically or somewhat obliquely 

 sunk pits, which may be four feet deep and is scarcely dis- 

 tinguishable from those of Th. tœnioides. I must say, however, 

 that I have never had an opportunity of discovering on the 

 sea-bottom the external opening of the pit inhabited by the pre- 

 sent species. Nor have I ever been able to see the outstretched 

 proboscis of the worm on the bottom, notwithstanding the special 

 searches I have made. This, coupled with the fact that the 

 species so long escaped the notice of collectors in spite of the 

 peculiar and conspicuous coloring of the proboscis, makes me 

 think that the protrusion of this organ out of the hiding place, 

 takes place under limited physical conditions, probably in the 

 night time only. 



As already indicated, the species is much alike Th. tœnioides 

 in points of size, shape and color, though there exist remarkable 

 differences in details and especially in the internal structure. 



The proboscis, as measured on living specimens held in cap- 

 tivity, is 30-40 cm. long and 1.7-2 cm. broad in the broadest 

 part, which is at the base. It is therefore considerably shorter 

 and somewhat broader than in Th. tœnioides. The ground color 

 is a clear yellow, which deepens in tone towards the base and 

 along the free margin. The somewhat concave ventral aspect 

 of the organ is marked in the distal parts with a fine and irregular 

 network of a bright green color. The network is distinct for an 

 extent of 6 cm. or more from the tip ; proximally it grows gradually 

 less distinct, at the same time assuming the form of fine transverse 

 stripes. Finally, at about lö cm. distance from the tip, the 



