116 MR. F. J. MEGGITT ON A 
scolex appears to have a terminal depression similar to that 
of Schistocephalus dimorphus Crepl. On the other hand, the 
suckers may stand out as small cups at the four corners of the 
base of a tetragonal pyramid, the apex being formed by the 
fifth sucker (Pl. I. fig. 2): the scolex may also be inserted in the 
neck like a cork ina bottle (Pl. I. fig. 1). It is obvious, there- 
fore, that the shape of the scolex is a character to which little 
importance can be attached. In life the head undergoes a 
regular series of changes, passing from an extremely elongated 
phase to a violently contracted and spherical one (text-fig. 1). 
Text-figure 1. 
Movements of scolex of Ichthyotenia filicollis. XX 142. 
The diameter of the head varies from ‘166 to -2 mm., and of 
the suckers from ‘04 to ‘07 mm. The neck is relatively long, and 
occupies about a quarter of the whole length. The first pro- 
glottis separated from it is much broader than long, its 
dimensions being 192-397 mm. broad x ‘1-166 mm. long. 
The total number of segments varies from 24 to 33, Kraemer 
states that the first proglottis is much longer than broad ; while 
Benedict figures two varieties, in one of which it is longer than 
broad, and in the other is broader than long. Liihe (17) gives 
it as longer than broad. The following table gives the external 
measurements according to various observers (Table A). Poste- 
riorly, the segments become longer in proportion to their width, 
until the penultimate proglottis is 1j-2 times as long as wide. 
The posterior proglottis is rounded at the tip, and at its apex is the 
excretory pore. In my specimens this was often very prominent, 
opening on a small triangular papilla. 
The separation of the proglottides from one another is very 
indistinct, being indicated in the posterior portion of the stro- 
bilus only by a slight notch. 
The genital openings are lateral, and alternate irregularly. 
According to Benedict, there is a small genital sinus, while 
