488 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [36] 
Millimeters. 
Breadth of basal bulb of neck ....-. Soece da aoe atae aes eee eae seiner eee 0.39 . 
Breadth of constriction between neck and body ....-.....-.--.-..--e0.------ 0.20 
Breadth of body just behind basal bulb of neck ...-.....2..-.-. 1-2-2 seen 0, 28 
Breadth of body (7 4™™ from neck, 25 ~t2\< cw ecelimacne ae scm elehlle aa ee Eee 0, 28 
Distance from neck to first stris 2 6 o.P soon cl ok wtons ve ae bemoans eee eee 11. 20 
Distaneo'from neck to first segment --.- 3. he occas nen s eau re come whee 14. 60 
Length of first segments indicated by striw ...-.....-..----....-----.. (5 Dee 0. 40 
Breadth of first segments indicated by striv ........---. 2-2-2. 022 --- see enee 0. 44 
Lengihof fret: distinc) segmoents:.). <<) nn. lee ste ase neceenieceen po = enn aeneee 0. 94 
Breadth of first distinctisegments. 22 oc... se. J. ose oe necwles cece a nee 0. 44 
DGNSTH Of TABU KOLINENTS 5. ou - oan wine <ool= cee able die sp alee smaaiee = ee 3. 00 
BRSAU GAOL las SEO MENLS i fo0 vec c ia mncioce al stajs eae beln Hones. eee 0. 80 
SFoRtth OfaPLODOSCIG3 2 fac ctiacsbwelseee upoemels asic dee es cee ence ae See eee 0. 33 
Wen min) wp nOOks. tcc tee sperm pees eMenne =~ ie ei einele in/near ate lene 0. 0075 
er eun of longest hooks : sts aiscer bie nts sie pele & Ses wee essa Omen ne 0. 009 
These worms are actively locomotile while living. 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 canis), in spiral intestine. Wood’s 
Holl, Mass., August, 1884. 
Family TETRACOTYLEZE Diesing. 
TANIA Linn. 
Tenia 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 iveepUIaH, 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 Tenia was obtained from the in- 
testine of the Common Eel (Anguilla vulgaris) August 26,1885. The 
