740 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [22] 



In many of these specimens the segments become rather indistinct 

 near the posterior end on account of transverse wrinkles on the seg- 

 ments which resemble the dividing line between two segments. In No. 

 4 the segments 12 mm from the posterior end are 3.5 mm wide and .5 mm 

 long. The last but one measures l mm in length and 1.8 mm in breadth 

 at the front end, narrowing to 1.2 mm at the posterior end. The last seg- 

 ment is 1.4 mm broad and 1.25 mm long, tapering to a bluntly rounded 

 point. 



The following measurements are introduced for the purpose of fur- 

 nishing a basis of comparison between the two varieties. It will be 

 observed that No. 1 differs uniformly in its head dimensions from the 

 others, between which there are but few differences. No. 1 is var. a, 

 the others are var. /?. 



Dimensions. 



Length 



Length of bothria 



Breadth of head, anterior, marginal 



Breadth of head, anterior, lateral 



Breadth of head, posterior, marginal 



Breadth of head, posterior, lateral 



Breadth of first segment, anterior, marginal 



Breadth of first segment, anterior, lateral 



Breadth of first segment, posterior, marginal t 



Breadth of first segment, posterior, lateral 



Length of first segment 



No.l. 



No. 2. 



No. 3. 



No. 4. 



mm. 



mm. 



mm. 



mm. 



655. 00 



470. 00 



534. 00 



610. 00 



0.86 



1.54 



1.60 



1.54 



0.44 



0.74 



0.80 



0.76 



0.48 



0.80 



0.80 



0.74 



0.70 



1.36 



1.34 



1.40 



0.54 



0.84 



0.80 



0.76 



0.18 



0.40 



0.68 



0.50 



0.50 



0.90 



0.90 



0.80 



0.50 



0.80 



1.06 



0.76 



0.56 



1.24 



1.26 



1.22 



0.26 



0.30 



0.34 



0.36 



No. 5. 



mm. 



660. 00 

 1.80 

 0.78 

 0.78 

 1.46 

 0.80 

 0.66 

 0.90 

 1.08 

 1.42 

 0.32 



Some of the measurements in numbers 2 to 5 marked first segment 

 were really taken from the second segment, on account of the anterior 

 part of the first segment being obscured by the overlapping bothria. 

 The difference between the first and second segments is, however, in 

 all cases very slight. 



In variety a one of the lateral faces is marked by two distinct linear 

 grooves, parallel with the margins, each about 1.5 mm from the nearest 

 margin. These are not distinct until about 125 mra back of the head; are 

 most distinct in the middle of the body, but continue to the posterior 

 end. Similar lines occur on the opposite face, but they are very faint. 

 They probably outline the water vascular canals. They were not seen 

 in the other specimens. 



The presence of ova is indicated in the alcoholic specimens by a dark 

 median line which, in var. a, begins 135 mm back of the head, and con- 

 tinues to within 6 mm of the posterior end. In the other specimens the 

 ova begin at about the same point. In some (Fig. 9) the ova continue 

 to the last segment, and the posterior segments are rather distinct. In 

 one individual of var. fi there is the same kind of termination to the 

 body as in var. a. Several of the specimens had been mutilated in collect- 



