NEW MAMMALIAN TAPEWORMS. 1005 



actually large size of the head but by the fact that the first strobila 

 are much narrower than those immediately following, and thus 

 an apparent constriction occurs which emphasizes the distinction 

 of the head. In other cases the conditions are apparently the 

 same ; but an examination with a lens shows that though a 

 constriction at about the same distance from the rostellum exists, 

 the formation of strobila exists beyond this point and has invaded 

 the hinder region of the actual scolex. It is a little difiicult 

 therefore to assert that a neck is or is not characteristic of 

 Anoplotcenia dasyuri. The occasional commencement of 

 strobilisation immediately behind the scolex is not unsuggestive 

 of Oochoristica*, with which genvis the present has some likeness, 

 and there is in the same way a kind of hint of a commencing 

 pseudoscolex. 



The body of the worm is about an inch in length or sometimes 

 rather longer ; but it never gi-ows to a great size. The segments 

 which immediately follow the head are very short ; but this 

 region of the body is not long, perhaps a couple of millimetres, and 

 contains but few segments, in some cases not more than a dozen, 

 in others rather more. The segments increase gradually in 

 length and towards the end of the body come to be three or four 

 times as long as they are broad. In the hinder segments the 

 genital pores are sometimes quite obvious when the worm is 

 examined with a lens, and irregularly alternate in position from 

 one side of the body to the other. In transverse sections the 

 body is apt to be hourglass-shaped owing to the greater thickness 

 of the lateral edges of the body due to the bulging caused by 

 the unusually large cirrus sacs. This is certainly the case with 

 the shorter and flatter anterior proglottids. 



In transverse sections, through the anterior region of the body 

 in mature segments, which are, however, not long and distended 

 with ova, the layers of the cortex can be readily distinguished. 

 The cortex (text-fig. 209) is of about the same diameter as the 

 medullary portion. It is distinguishable into a much thicker 

 outer layer of longitudinal fibres, and a much thinner inner 

 layer of longitudinal fibres. The two are separated by delicate 

 transversely-running fibres, of which there are also a set 

 within the inner layer of longitudinal fibres and thus bordering 

 upon the medulla. The inner layer of longitudinal fibres is 

 particularly conspicuous for the reason that several are closely 

 grouped into a bundle, of which bundles there is only a single 

 row, as is shown in text-figure 209. This arrangement of the 

 muscular fibres is only apparent in the more anterior segments. 

 It ceases to be obvious in ripe proglottids such as that represented 

 in text-fig. 213 (p. 1012) wdiere the body is gorged with eggs. 

 In these segments however, where, as will be pointed out at 

 length presently, the eggs ai-e partly contained in a uterus and 

 partly scattered singly or in groups through the medullary 



* Sec P. Z. S. 1911, p. 628. 



