NEW CESTODES FROM THE TASMANIAN DEVIL. 685 



describe in the strobila and even in the neck-region of the same. 

 In the medullary region at either end is to be seen the water 

 vascular tube, which is here rather coiled, a tube appearing five 

 or six times in a single cross section. In the middle of the 

 medullary area are certain remarkable structures, which are 

 represented in text-fig. 94 (p. 679). These are apparently 

 hollow spheres excavated in the parenchyma but with very 

 definite walls. These vesicles contain lumps of an amorphous 

 matter into the nature of which I have not enquired. There 

 is no connection that I could find betwfeen these vesicles and 

 the water vascukxr system. I am quite uncertain as to their 

 nature. 



The neck-region of the worm after it has issued from the cyst 

 which contains the scolex is represented in transverse section in 

 text-fig. 97. It will be observed at once that the medullary 

 parenchyma is very greatly reduced. It forms a thin layer very 

 much narrower than the extremely thick cortical layer. Nor 

 could I discern in it the typical retiform appearance of the 

 Cestoid medullary parenchyma with spherical masses of granular 

 matter lying between the meshes of the network. The whole of 

 the available space, save between the individual testes at the two 

 sides of each proglottid, is occupied by the rudimentaiy female 

 organs, which together with the testes seem to occur in the veiy 

 first segments. The whole space thus occupied by the generative 

 masses and by what remains of the medullary parenchyma is not 

 one half of the diameter of the cortex. It has been already 

 pointed out that at the posterior end of the scolex, a little before 

 it merges with the neck, the medulla is surrounded by a very 

 thick layer of muscles composed of large fibres. In this layer no 

 marked arrangement of the fibres into bundles could be made 

 out. But in the next few sections, which we here speak of as 

 the neck, these fibres are very definitely disposed in a series of 

 bundles (text-fig. 98). 



These bundles are disposed in four to six layers, and at the 

 two lateral extremities of each segment they are rather more 

 numerous than medianly. The bundles consist of a large number 

 of individual fibres, often as many as sixty or so. They are sepa- 

 rated from each other by a dense nucleated tissue. Later in the 

 body we have the same four to six rows of bundles of fibres ; 

 but in these latter segments each row is separated from those 

 which lie above and below it by a delicate layer of transverse 

 fibres. These fibres are not apparent in the neck-region. I 

 imagine that this enormously powerful muscular system is corre- 

 lated with the distance to which the scolex is enabled to force 

 itself into the wall of the intestine of its host. These rows of 

 bundles of longitudinal fibres are reminiscent of what is charac- 

 teristic of the family Acoleidae, as is to be seen, for example, in 

 the genus FroterogynotcBnia* where they have been* figured by 



* A1)li. Seiick. Gcs. 1911, p. 260, fio;. 14. 



