546 A DESCRIPTION OF THE ENTOZOA COLLECTED BY DR WILLEY 



forty-two species and twenty-two genera of Cestodes from Fish or in Bronn's " Thierreich " 

 have I been able to find anything which I could regard as congeneric with the form 

 which I have ventured to name as above. 



The length of the animal, with ripe proglottides, as shown in Fig. 13, Plate LV., 

 averages about 4 to 5 cms., its breadth in the broadest part 1"5 mm. The grooves 

 dividing the anterior segments are deep, so that the edges project as conspicuous 

 flaps in the middle region of the body, the edges overlap to a very marked extent 

 the succeeding segments so that a transverse section usually cuts a given segment 

 where it is surrounded by the overlapping lips of the hinder border of the pre- 

 ceding proglottis. The section thus presents the appearance of a round disc lying in 

 a ring. 



The head consists of two very distinct parts, a rostellum and a very swollen and 

 enlarged collar. No hooks could be detected either in the living or dead specimens 

 or in sections through the head. The rostellum is firmly imbedded in the tissue of 

 the intestine of the host (Fig. 15, Plate LV.). The edges of the pocket in which it 

 lies have grown in round the neck of the rostellum ; there seems to be no other 

 means of attachment. There are no hooks and the suckers are both small and weak, 

 and not in contact with the tissues of the host. 



The collar is a large swollen structure. From the centre of its anterior face the 

 rostellum arises and on the same face, close to the base of the rostellum, four 

 minute and insignificant suckers are situated (Fig. 14, Plate LV.). In some notes 

 made by Dr Willey at the time of taking these parasites he states " the suckers are 

 not visible in the living condition." They are just visible in the spirit specimens 

 with a good binocular microscope under a 2 in. objective as four round spots placed 

 at the four ends of an equal limbed cross. In section (Fig. 15, Plate LV.) it will 

 be seen that the suckers are very small and unattached to the intestinal wall of the 

 Dog-fish. 



The tissue of the collar is a spongy mesh-work which absorbs but little pigment 

 when stained. The nuclei of the cells lining the thin cuticle however stain, and certain 

 large cells in the rostellum. The collar is traversed by four bands of stout muscles 

 which pass from the longitudinal muscles in the body to the rostellum, where they 

 spread out in a brush-like manner. These four bundles of muscles doubtless permit the 

 movement of the body on the fixed head. Posteriorly the muscles tend to split into 

 eight and then into more bundles, which ultimately end in the well-marked longitudinal 

 muscles of the neck. 



Anteriorly the body is circular in outline and the anterior end of even the mature 

 segments retain a circLdar outline, although the middle portion of each proglottis is 

 somewhat flattened. The most conspicuous feature of the anterior end of the animal 

 is the great development of the longitudinal muscles, these are very powerful and 

 regularly arranged in such a way as to recall the longitudinal muscles of an earth-worm. 



The dorsal and ventral lateral canals of the water-vascular system both persist, 

 the ventral is however much the larger. A rather conspicuous tube which appears in 

 the lower edge of the posterior flap of each proglottis, which overlaps and partially 

 conceals the anterior half of the succeeding, almost certainly belongs to this system. 



