784 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [66~] 



usually a little iu frout of the middle point. The cirrus is very long 

 and. so far as could be made out, is smooth. In order to determine the 

 exact position of the vagina it was necessary to make an examination 

 of thin sections. 



One of the two specimens of var. fi, after having lain for twenty-four 

 hours in sea-water, measured 75 mm in length. For the first 35 mm the 

 segments were much crowded and several times as broad as long. The 

 posterior half consisted of segments about as long as broad. The ex- 

 treme posterior segments were a little longer than broad. The pos- 

 terior half of the body was much narrower than the antero-mediau part. 



Following are measurements of the living specimens var. (3. Length 

 75 mm ; lateral breadth of disk, 5 mm ; marginal breadth of disk, 4.5 mm ; thick- 

 ness of disk, l.l mm ; diameter of cervical mass, 2. L mm ; length, l.5 mm ; 

 breadth of body immediately behind head, 1.15 lum ; thickness at same 

 point, .35 mm ; greatest breadth of body, 2.45 mm ; leugth of posterior seg- 

 ments, 1.4 mm ; breadth of posterior segments, 1.3 mra . 



The strobile, particularly in the vicinity of the median segments, was 

 very active and constantly changing its shape by alternate contraction 

 and expansion. 



The smaller specimen of var. a was not measured while living, but as 

 an alcoholic specimen, measured 40 mm in length ; the two diameters of 

 the disk 2.1 mm and 2.2 mm , respectively; thickness of disk, .9G mm ; diameter 

 of cervical mass, ,86 mm ; length of cervical mass, .44 lum . 



This specimen exhibited a phenomenon in the anterior part of the 

 body, which, if not the result of mutilation, is a curious abnormal freak. 

 For a distance of about 16 mm back of the head, beginning at the base of 

 the cervical mass, the body is double. It appears to be double at the 

 point where it leaves the head and where inclosed by the ruffle-like 

 folds of the base of the organ. 



A few small, slender, fusiform free segments were found associated with 

 these worms, of which they were at first taken to be the mature pro- 

 glottides. They were about 3 mm long and l ram broad. After a careful 

 examination of these segments 1 find that they do not belong to the 

 mature strobile^ and I am disposed to regard them as belonging to some 

 other cestod. 



It is worthy of note that no parasites were obtained from this shark 

 except the four individuals mentioned in this description, and these free 

 segments, eight or ten in number. The only parts of the shark that 

 were brought into the laboratory were the head and viscera. They were 

 then identified as belonging to a specimen of Carcharias obscurus. I am 

 almost tempted now to doubt the validity of the identification, since the 

 parasites are so very different from what I have been accustomed to 

 find in C. obscurus. 



The cervical mass in the adult specimen was not so distinctly yellow 

 as in the others, moreover the anterior part of the body, immediately 

 behind it, exhibited a faint pinkish tinge, a feature which was not ob- 

 served in the others, 



