THE TAPEWORMS (CESTODA] OF THE RED GROUSE 343 



down the alimentary canal on their way to the exterior, but the tapeworm as an 

 individual lives only in the duodenum. 



H. microps is a very long worm, attaining in the longest examples a length of 

 some 15-16 cms. It consists of an enormous number of proglottides. The first two 

 millimetres which come after the head contain as many as sixty to seventy 

 segments, and lower down the body, where the proglottides were mature, as many 

 as ten proglottides measured but 1 mm. Of course these measurements depend 

 entirely on the state of the contraction of the worm, but if we take the mean 

 between them as a rough average approximation we shall get the astonishing 

 number of three thousand proglottides in a single specimen. As each proglottis 

 contains a large number of eggs, and as they are being continually renewed, and 

 as, further, the number of tapeworms in the duodenum amounts to hundreds, it 

 is easy to see that a Grouse moor must be peppered with ova. 



The head is somewhat squarish, with a central retractile rostellum and four 

 suckers at the corners. The rostellum is surrounded by a closely-packed ring of 

 very numerous spines or hooks. These are very minute and, except in the fresh 

 specimen, very difficult to see, even then it requires an immersion - lens to 

 make out anything of their structure. Their proximal end is rounded, and then 

 comes a constriction ; the spine then thickens till about the middle of its length, 

 when it tapers to a very fine point. Although these spines are slightly curved, 

 they are in no sense hooked (PL LI., Fig. 6). I have tried to measure the 

 length of these spines from specimens of the head, which has been cut in sections. 

 I am not quite sure that the hooks were entire, and so am not quite sure that my 

 measurement is large enough, but I should put their length at about 16 M certainly 

 not less. The hooks seem to be in a single row, and very close together. 



The suckers are deep and well marked, but it must always be borne in mind 

 how very small the head is, and corresponding with this the suckers are also very 

 minute. 



The posterior edge of each proglottis is " sailliant," but it does not overhang 

 the succeeding proglottis ; it stands out like the tooth of a saw, and viewed laterally 

 the side of this worm is very saw-like. Throughout the body the proglottides are 

 much broader than they are long. In the older ones there are numerous calcareous 

 bodies, the measurements of which Wolffhttgel gives as O'OIS mm. by O'Ol mm. 



The genital pore is on the same side in all the segments ; the left side, judging by 

 the orientation suggested by the female reproductive organs, being on the ventral 

 surface. The vagina opens into a peculiarly large and muscular receptaculum 



