G ART. II. A. IZÜKA : OBSERVATIONS ON THE 



dimensions should be exceedingly variable. It may in general 

 be said that they attain a length of 200-250 mm. and a breadth 

 of 3 or 4 mm. The number of segments varies of course ac- 

 cording to the size of the specimens ; in a large one there 

 may be as many as 300. The addition of new segments 

 during growth takes place, one by one, invariably in front of 

 the pygidium. 



Gradually from the head end backwards the breadth in- 

 creases slightly to about the tenth segment, then it continues 

 nearly the same to about the 40 th or 50 th segment, beyond 

 which the body again begins to taper very gradually towards the 

 hindmost region, which may be said to be ver\ r slender. 



The size of the segments stands in direct proportion to the 

 breadth of the region to which they belong. In respect of their 

 structure, both internal and external, the segments are all 

 essentially alike so that a demarcation into thoracic and abdominal 

 segments can not be carried out. 



Color. — In the living state of average specimens, the dorsum 

 (PI. I., fig. 1) in the anteriormost region is dusky brown with a 

 purplish iridescence. In the main portion of the ^body, this color 

 gradually passes posteriorly into a deep red, which again gradually 

 becomes somewhat lighter towards the hind end. On the prse- 

 stomium the bluish brown pigments are developed in small 

 irregular, sometimes eye-like, blotches. The parapodia are always 

 of a much lighter hue than the segments to which they belong. 

 The dorsal median blood-vessel is prominently visible as a deep 

 red line, in which the postero-anteriorly directed peristalsis may 

 be distinctly observed. 



Seen on the ventral side, the peristomium and a few succeeding 



