587 



three-fourths of the arm. Of the four following rows, only the inner 

 suckers are developed, while the outer ones are represented only by the 

 stalks. These four suckers are moreover not placed in a continuous 

 series, but the two proximal ones are of 22nd and 23rd, and the two distal 

 ones belong to the 25th and the 26th, while the 24th is only represented 

 by a stalk. That this sucker has lost its head can be imagined from 

 other specimens described below, which also show that there exist some 

 irregularities in the formation, as well as the number and the arrange- 

 ment, of the suckers at the distal portion of the arm. The supporting 

 membrane of the transverse bars is nearly equally developed on both 

 sides of it to 21st sucker, which is situated at about two-thirds the length 

 of the suckered portion of the arm from the proximal end. From this 

 point distally the membrane as well as the transverse bars become rudi- 

 mentary on the outer side, the traces of the bar being seen to the 22 nd 

 sucker, on the outer side of which the bar appears only as a small knob, 

 while the membrane can be traced a little more distally, i. e. as far as 

 the 23rd sucker. The peduncles of the suckers persist, however, up to 

 the very tijî of the arm, becoming thin and membraneous distally. On 

 the inner side, the transverse bars as well as the membrane persist to 

 the tip of the arm, but the peduncles of the suckers become rudimen- 

 tary as we proceed more distally to about the 35 throw, where they be- 

 come entirely lost. Thus it will be seen that on the outer side the pe- 

 duncles of the suckers only persist, while the heads, the tranverse bars 

 together with the supporting membrane become lost, whereas on the 

 inner side the transverse bars and the supporting membrane persist, 

 while the heads and the peduncles of the suckers become rudimentary. 



The position of the transverse bars of the inner side, which, as 

 above stated, persist to the tip of the arm, is transverse proximally, but 

 becomes more and more oblique distally, the free ends facing distally in- 

 wards. The position of the peduncles of the suckers on the outer side 

 also change their direction from the point where they lose their heads, 

 the free ends becoming directed inward and distally like the bars of the 

 outer row, the two structures are thus placed in the same direction. It 

 will moreover be observed that the peduncles of the suckers on the outer 

 side become greatly enlarged after they have lost their heads, thus give 

 the appearance of being transformed from the transverse bars of the 

 membrane. That this however is not the case, can be seen by tracing their 

 development. 



Some variations are to be observed in the formation of the hecto- 

 cotylized arm between different individuals. Thus in a specimens from 

 I^iigata, on the coast of the Japan Sea, labelled as (B 2) (Fig. 2) in our 

 Collection, which has exactly the same mantle length as the Misaki 



