THE GEPHYREA OF JAPAN. 15 



bridges which mostly arise from the nodal points of the reticnlnm. 

 It scarcely needs to be pointed out that the bridges as well as 

 the trabeculee are covered by the peritoneum. I am at present 

 quite at a loss to explain the physiological significance of the 

 structure. Possibly it is nothing but a certain pathological 

 product. 



Genm PHASCOLION. 



PHASCOLION RECTUS, n. sp. 



(Figs. 45-49). 



This new species is based on a single specimen which was 

 obtained, September 1903, from a depth of 400 h'lro in the 

 Sagami Bay by means of the long-line (Dabonawa). It has been 

 carefully preserved in alcohol. 



The worm inhabits the dead shell of a Dentaliuin, the in- 

 trovert partially protruding out of the Larger aperture. The 

 body not being cemented to the shell lies free. The entire 

 length of the worm is about 35 mm., nearly one-third of which 

 constitutes the partly retracted introvert (Fig. A^)). The body 

 proper is nearly straight, gently swollen in the middle where it 

 measures about 2 mm. across, while the introvert is relatively 

 thick and about 1 myn. broad. The skin is of a grayish yellow 



