336 THE GROUSE IN HEALTH AND IN DISEASE 



at about the same, but here, as elsewhere, no two specimens are exactly alike. The 

 proglottides which follow are extremely narrow from behind forward, but they very 

 rapidly increase in breadth, so that 6 or 7 mm. from the head the breadth is 1 mm., 

 and at about 12 to 15 mm. it is 2 mm. The greatest breadth is usually about 

 2'5 mm. to 3 mm., but in some specimens 4 mm. is reached (PI. L., Fig. 2). 

 The broadest portion is usually about the third quarter of the body from the head ; 

 even here the segments still have but a very shallow antero-posterior diameter, 

 about 0'6 mm. to 1 mm. Behind this region the segments narrow again. They 

 become as long as they are broad, and but for the prominent posterior lip the 

 segments would be square. The posterior segments are, however, longer than they 

 are broad, and quite at the hinder end they are attached to one another by but a 

 slender connection. The prominent posterior angle is maintained to the last (vide 

 PL L., Fig. 2). It is, however, difficult to give precise statements as to the con- 

 dition of this worm. In some, one region of the body will be swollen out ; in 

 other specimens, other regions will expand. Some have a thin, papery consistence ; 

 others are plump and almost circular in section. Sometimes the posterior rim 

 overlaps the anterior region of the succeeding segment, so that the whole resembles 

 the pile of conical caps which clowns used I do not know whether they still do 

 so to wear in the circus. These varying conditions doubtless depend largely on 

 the state of the parasites when killed, and on the means taken to kill them. The 

 genital pore is, except in rare cases, on one and the same side. 



The anterior end tapers quickly to the very small, squarish head. Anteriorly, 

 the head ends in a rostellum, which seems nearly always to be retracted into a 

 shallow recess. At each of its four corners the head bears a large sucker, as a 

 rule circular, but at times oval in shape, and then the long axis is longitudinal 

 (PI. LI., Fig. 1). 



Both rostellum and suckers bear hooks, which differ, however, both in their 

 arrangement and shape. The hooks of the rostellum are arranged in a double row. 

 Each is shaped something between a Y and a T, one arm being more curved than 

 the other, and it is this arm which is anterior. The stalk of the hook is but very 

 slightly curved, and the posterior row alternates with the anterior. The length of 

 the hooks is between 6'9 M and 6 '6^. The shape of the hooks does not vary 

 appreciably, and the arrangement in two rings is very regular. These hooks were 

 not seen by Baird, and were first recognised in 1891 l (PL LI., Fig. 3). 



The hooks on the suckers are also very minute, and they vary considerably in 



1 F. S. Monticelli, "Boll. Soc. Napoli," Ser. I. v. p. 155, 1891. 



