488 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [36] 



Millimeters. 



Breadth of basal bulb of neck 0.39 



Breadth of constriction between neck and body 0.20 



Breadth of body just behind basal bulb of neck 0.28 



Breadth of body 7.4 mm from neck 0.28 



Distance from neck to first striae 11.20 



Distance from neck to first segment 14. 60 



Length of first segments indicated by strise 0. 40 



Breadth of first segments indicated by striaj 0. 44 



Length of first distinct segments '. 0.94 



Breadth of first distinct segments 0. 44 



Length of last segments 3. 00 



Breadth of last segments 0. 80 



Breadth of proboscis 0. 33 



Length of hooks 0.0075 



Length of longest hooks 0. 009 



These worms are actively locornotile while liviug. The two bothria 

 act as sucking disks and change their shape continuously. As the head 

 progresses the anterior ends of the proboscis sheaths separate slightly, 

 when the soft tissue which forms the anterior end of the head is then 

 drawn in so as to give to the front of the head the shape. of a hollow 

 cup; the anterior ends of the sheaths then approach each other and 

 the hollow cup disappears, the tissue which forms it being thrust out 

 into a short, blunt eminence (myzorhynchus). 



Habitat. — Smooth Dogfish (Mustelus ca?iis), in spiral intestine. Wood's 

 Holl, Mass., August, 1884. 



Family TETBACOTYLExE Biesing. 

 Taenia Linn. 

 Taenia dilatata, sp. nov. 



[Plate V, Figs. 14-16.] 



Head small, truncate, or, in living specimens, slightly prominent in 

 front. Acetabula nearly circular, directed a little forwards. Neck 

 rugose, very long, very contractile and dilatable, narrow in front, 

 tapering toward the head; a short distance back of the head expand- 

 ing into a number of irregular, transparent, dilated folds, which border 

 both sides of an opaque central portion, in which two longitudinal 

 canals are faintly outlined. First segments about three times as broad 

 as long ; median segments square, or broader than long ; ultimate seg- 

 ments nearly square, sometimes broader than long, sometimes longer 

 than broad. Genital apertures marginal, opening a very little in front 

 of the middle. 



A single specimen of this species of Taenia was obtained from the in- 

 testine of the Common Eel (Anguilla vulgaris) August 2(5, 1885. The 



