822 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [104] 



low, as are also the basal supports ami, in fact, the whole system, with 

 the exception of the short bar which connects the long basal support 

 of the inner set with the shorter prolongations of the outer set. 



The neck is very long and slender. No distinct segments occur un 

 til 25 mm or 30 lum back of the head. The first segments are squarish ; 

 the succeeding segments increase in length slowly ; median segments 

 square, becoming subcircular in outline, and towards posterior end elon- 

 gated ; last segments three or four times as long as broad and in life 

 somewhat cylindrical. 



Genital apertures marginal, near middle of segment, male and female 

 approximate. Length G7 mm . 



Habitat. Carcharius obscurus, spiral valve, a single specimen. Wood's 

 Holl, Massachusetts, August 12, 1887. 



The following measurements were made on the living specimen held 

 in place by slight compression : 



Length, 67 mm ; length of head, .52 mm ; greatest diameter of head, 

 .54111111 . diameter in front of hooks, .20 mm ; diameter, posterior, .24 mm ; 

 thickness of head, .24"""; greatest breadth of single bothrium, ,26 min ; 

 length of hooks, .16 mm ; lateral diameter of neck, .08 mm ; marginal di- 

 ameter, .OG mra j length of neck, about 16 mni ; length of first distinct seg- 

 ments, .10 mm ; breadth, .26 mm ; length of postero-mediau segments, .60 mm ; 

 breadth, .36 mm j length of last segments, 1.40; breadth, .40 lum . 



With regard to the occurrence of supplemental disks in this species I 

 am in some doubt. When the living worm was first examined the sketch 

 which my wife made of it showed that the anterior ends of the bothria 

 were somewhat elongated and rounded, with a circular depression 

 showing plainly in each. When I examined the specimen an hour or 

 two later, in order to obtain measurements, the anterior ends of the 

 bothria were abruptly truncated and there was no sign of circular de- 

 pressions. Afterwards, when the worm, as an alcoholic specimen, 

 was transferred to glycerine, something like supplemental disks were 

 faintly visible. These are circular and about .033 mm in diameter. It 

 would appear that the anterior ends of the bothria contract or fold in- 

 ward, thus obscuring the faint depression, which is probably to be re- 

 garded as a supplemental disk. 



When the posterior segments were flattened out in glycerine they 

 appeared quite regular in outline, rectangular, and somewhat confluent, 

 so as to give to the margins of the strobile in places a gently undulat- 

 ing outline. None of the segments are mature. The posterior seg- 

 ments are filled with granular bodies about .03 mm in diameter. These 

 bodies are globular in shape in the anterior part of the segment. In 

 the posterior part of the segment they are more irregular and collected 

 into large elongated masses. These granular masses extend to the 

 extreme posterior edge of the segment, while at the anterior end there 

 is a space of clear, finely granular tissue, which extends backward 

 along each margin between the central granular masses and the ex- 

 ternal cuticular layer. 



