1909. | TAPE-WORMS OF THE RED GROUSE. 359 
Before giving some anatomical details of H. microps it is worth 
mentioning that Wolffhiigel found fragments of this species— 
none with the head—in the small intestine, large intestine, and 
end—he does not say which end—of the ceca of Tetrao urogallus. 
We have also found short chains of ripe proglottides passing 
down the alimentary canal on their way to the exterior, but the 
tape-worm 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 ems. It consists of an enormous 
number of proglottides. The first two millimetres which come 
after the head contain as many as 60-70 segments, and lower 
down the body, where the proglottides were mature, as many as 
10 proglottides measured but 1 mm. Of course these measure- 
ments 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 3000 
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 tape-worms in the duodenum 
amounts to hundreds, it is easy to see that a grouse-moor must 
be just peppered over with ova (Pl. LVILI. fig. 4). 
The head is somewhat squarish (Pl, LX. fig. 18), with a central 
retractile rostellum and four suckers at the corners. The ros- 
tellum is surrounded by a closely packed ring of very numerous 
spines or hooks (Pl. LX. figs. 19 & 20). These are very minute 
and, except in the fresh specimen, very ditticult to see, and 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 and then tapers to a very fine point. Although these 
spines are slightly curved, they are in no sense hooked (PI. LX. 
fig. 20). 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 quife sure 
that my measurement is large enough, but I should put their 
length at avout 16 ~—certainly not less. The hooks seem to be in 
a single row, but 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 arelong. In the older ones there are numerous 
calcareous bodies, the measurements of which Wolffhiigel gives as 
0:018 mm. by 0°01 mm. (Pl. LX. fig. 21). 
The genital pore is in all the segments on the same side; the 
left, judging by the orientation suggested by the female repro- 
ductive organs, being on the ventral surface. The vagina opens 
