284 



AKIRA IZUKA : 



low and the eyes of a brownish black color. In the state preserved in al- 

 cohol the colors, except that of the eyes, have entirely faded away. 



Form. — The body is elongate and dorso-ventrally much flattened, be- 

 ing only 0.7 mm. thick. Dorso-ventral differentiation very slight ; dorsum 

 slightly convex ; ventral surface plane, longitudinally bisected by a narrow 

 median welt bounded by two fine parallel grooves. The body narrows 

 towards both ends, somewhat more gradually towards the pygidium than 

 towards the head. Entire length of body 21.0 mm.; Maximum breadth 

 including parapodia 2.2 mm. at about the posterior end of the anterior 

 third of the body. Segments short and numerous (in all about 260 in 

 number); longest parapodium equal in length to about one-sixth of the trunk. 



Prcestomium (Fig. 1.) comparatively small; when viewed from the 

 dorsum, it appears to be broader in front than behind, being distinctly 



bilobed. Ocular region on each 

 side elevated into a prominent 

 subelliptical lobe, which extends a 

 considerable distance behind the 

 posterior eye. The two pairs of 

 eyes situated as usual in the arms 

 of the letter V. Anterior eye 

 about twice the posterior in dia- 

 meter, somewhat ovoid in shape 

 and with a trace of a lens ; 

 directed slightly forwards and 

 upwards. The second pair of 

 eyes follows the first with a short 

 interspace ; round in shape. The 

 median tentaculum springs from 

 Fig. 1. -Anterior extremity of T. mUakiensis. n. sp. the dorsal surface of praestomium 

 2o/?naturIî e sTze. at about the level of the anterior 



pair of eyes, while the paired tentacula originate from the anterior end 

 of prsestomial lobes. All the three tenatcula are of nearly the same 

 length and are annulated, similarly to peristomial and dorsal cirri ; they are 



