REPORT OF COMMISSIONER OF FISH AND FISHERIES. [124" 



small hooks are arranged in double transverse rows between the trans 

 verse rows of large hooks. In this case the hooks in the anterior row 

 are much longer than those in the posterior row, while in both the hooks 

 are slender. On the side of the proboscis opposite the row of broad, 

 stout hooks there is, at least at the base of the proboscis, a longitud] 

 nal space in which there are no large hooks. This space is densely 

 covered with small hooks, which are very short, with broad bases. 

 There appear to be about nine longitudinal rows of large hooks, the 

 hooks iu each row differing more or less from those in every other. 

 The figures (Figs. 8 and 9, Plate xn), while not showing all the varie- 

 ties of hooks, nor their arrangement in toto, give a very correct idea of 

 the kind of hooks and their arrangement. 



Transverse striae, indicating the beginning of segments, begin about 

 0.4""" back of the contractile bulbs. The first distinct segments are 

 0.6""" wide and O.OG""" long. One of the posterior segments had the 

 following dimensions: Length, 2.4"""; breadth, anterior 1.2""", at mar- 

 giual aperture 1.48'"% posterior 1'"'" ; thickness, 0.9""" ; marginal geni- 

 tal aperture about 0.7""" from the posterior end. When the cirrus is 

 retracted it leaves a rectangular notch or emargination, with rounded, 

 projecting lips. The cirrus was partly everted in one segment; it 

 scarcely extended beyond the marginal notch, which it filled completely. 

 It measured 0.12""" in length and 0.1"" in diameter, was smooth, tumid 

 at outer end and at base, with constriction in the middle. 



When placed in glycerine the posterior segments are seen to be 

 marked with a number fourteen, more or less of longitudinal strire, 

 which converge at the two extremities near the median line, whence 

 they radiate like meridian lines from the poles of a globe. 



Anatomy of posterior segments. An examination of a few thin sections 

 of posterior segments yields the following rather meager data : The 

 ovaries lie near the base of the segment and consist of two paired, round- 

 ish organs, lying on either side of the median line, each about 0.2""" in 

 diameter, and made up of small, polygonal, nucleated cells 0.005""" in 

 diameter. A convoluted mass of one or more tubes lies immediately in 

 front of the ovaries, occupying the median line from the anterior edge of 

 the ovaries to a point a little in front of the cirrus bulb, thence it bends 

 back and communicates with the cirrus bulb. It is evidently, in part at 

 least, the vas deferens. In front of this convoluted mass there is a. 

 thick-walled tube of very different appearance, which extends along the 

 median line and appears to approach the exterior at the anterior edge 

 of the segment. This is probably the uterus, and its extremity at the 

 anterior edge of the segment an external orifice whence ova are ex- 

 pelled from ripe proglottides. I can find no trace of a vagina, unless 

 the thick-walled tube which I suppose to be the uterus should prove to 

 represent that organ. A very characteristic feature of these segments 

 is the strong bands of longitudinal striae which lie in the lateral walls., 

 Ova were observed in some of the sections. They lay in the postero- 



Dl 



