][EL M IN THO LOG ICA L N TES.—JO HNS TO X . 



ISO' 



In transverse sections of the anterior end of the scolex, the nuiscuhiture 

 is seen cut transversely and obliquely. Some of the fibres are inserted into the 

 apical region of tlie rostellum and diverge as they pass posteriorly, appearing 

 in the central region of the rostellum (tig. 3). Outwardly from these are more 

 or less transverse fibres which are inserted into the base of the suckers, and just 

 behind this area they become rather diagonally arranged as shown in fig. 4. 

 Lying internally from these are relatively few longitudinal fibres and the nerve- 

 ring. Just posteriorly, the arrangement of the musculature is as shown in 

 fig. 5, the obliquely transverse series now becoming a well-developed band of 

 transverse fibres situated dorsally and ventrally, each band connecting the 

 inner and lower portions of the two suckers of the respective surfaces. The 

 arrangement and position of these bands is such as to suggest that their contrac- 

 tion may cause the outer parts of the suckers to move away from each other. 

 Some of the oblique fibres are still seen in the section (fig. 5). Within the 

 transverse bands are the longitudinal nmsculature as well as less strongly 

 developed fibres arranged irregularly^ and traversing the medulla. 



At about the level of the base of the suckers (fig. 6) the longitudinal 

 series becomes much more evident, and can be seen aggregated particularity 

 around the inner margins of the suckers. Fibres also lie scattered in the medulla, 

 and there are weak ring-fibres situated outwardly from the sucker region in 

 the loose cortex below the subcuticula. 



Nervous System. — The nerve-ring (fig. 4) lies between the suckers at 

 about the level of the base of their concavities. In the neck and strobila the 

 longitudinal nerve of each side lies dorsolaterally to the main excretory canal 

 and apparently dorsally to the sex-ducts. 



Excretory System. — The state of 

 preservation of the specimens does not 

 allow of the tracing of the excretory 

 system forwards beyond the anterior 

 part of the neck, with any certainty. 

 The ventral vessel apparently forms 

 a loop just behind and outwardly 

 from the nerve-ring. The dorsal 

 canals do not extend into the prog- 

 lottids but can be recognised in sec- 

 tions of the neck (figs 7, 8, 9), and 

 their walls, as already stated, are pro- 

 vided with a ring of strong muscular 

 fibres like those of the rest of the 

 scolex and neck. The ventral vessel 

 of each side has a much wider lumen 

 and possesses thin walls. In the 

 specimen sectioned, the dorsal canals 

 show the following arrangement in 

 the scolex and neck. On the right side 

 in the posterior part of the scolex there 

 are three excretory ducts, but only two 

 on the other (fig. 7) . Two of each side 

 eventually fuse in the neck so that there come to be, in addition to the ventral 

 canal, one dorsal vessel on the left side and two on the right (fig. 8). This 



Fig. 9. — Portion of a transverse section in 

 the vicinity of that shown in fig. 8, showing 

 detailed structure of cortex and excretory 

 vessels. Lettering as in previous figures — 

 C.C., calcareous corpuscles ; cu., cuticle. 



