134 ART. II. A. IZUKA : 



is a bright yellowish-brown, deepest anteriorly and gradually dying 

 out on about the 3 0th segment. Posteriorly the body is nearly 

 colourless, unless the sexual products contained give it a pink 

 colour. 



The form of body is in life, as after preservation, flat below 

 and strongly arched above throughout its entire length. Body, 

 consisting of about 200 segments, measures about 95 mm. in 

 length and 4 mm. in breadth including parapodia. 



Prostomium broader than long, equal in length to peristomium, 

 bilobed on the anterior margin, and with a median groove 

 reacliing from the indentation posteriorly to base of the unpaired 

 median tentacle. The tentacles, though a little narrowed at their 

 bases, have no distinct ceratophore ; the middle one arises as a 

 rule in front of the origin of the other two, though they all 

 arise from nearly the same level. The form of eyes is characteristic ; 

 it varies from a narrow crescentic to a kidney or bean shape, 

 never beins^ oval. 



Dorsal and ventral cirri extend as far as tip of the para- 

 podium, or a little further in anterior parapodia. 



Compound bristles colourless ; shaft bent, its end distally 

 broadened to twice the diameter of the proximal parts, finely 

 denticulated near the distal end ; the end -piece short, being nearly 

 of the shape of an equilateral triangle, the end 2 -toothed, and 

 provided with a guard-hke wing showing fine striation. The 

 hooks always bear two distinct teeth, unless these be damaged 

 by wear as it sometimes happens ; seldom is their guard or 

 winging preserved. 



The mandibular plates are most characteristic in constitution 

 and form, being usually calcareous and provided with special 

 jjlates of a brown or black horny material. The number of teeth 



