62 ART. 4. — I. IKEDA : 



THALASSEMA OWSTONI, n. sp. 



( Thalassema diaphanes Sluiter. ?) 

 (Figs. 18, 96 & 97). 



The single specimen, on which this species is based, was 

 dredged by Mr. Owston together with the type specimen of 

 Phascolosoma owstoni, from a depth of 180 fathoms in the Uraga 

 Channel. It is small, measuring 17 mm. in length and 5 mm. in 

 breadth. The proboscis, about 7.5 m.7n. long, is deeply furrowed 

 longitudinally. The color, as preserved in formalin, is a pale 

 reddish brown. The skin is soft and smooth, except at both 

 extremities of the body proper, where the papillae are largest and 

 most closely aggregated. In the main middle region of the body 

 the papillte cannot be detected with the naked eye. There are 

 two comparatively large ventral hooks of a bright yellow color. 



The longitudinal muscles of the body-wall are thoroughout 

 continuous. Only a pair of small sac-like segmental organs are 

 situated just behind the ventral hooks (Fig. 96, so). They have 

 no spiral appendage, but are provided with a large ciliated funnel 

 (Fig. 97, fn). The erector (or the radial) muscles of the hooks 

 are well developed {em, Fig. 96) ; the interbasal muscle is very 

 long. Unfortunately the specimen is torn near the posterior end 

 of the body, so that the greater part of the alimentary canal 

 and of the anal glands has been lost. Inspite of this defect it 

 can be ascertained that there are present small ciliated funnels 



