ON A CESTODK FHOM DACliLO GIGAS, liODD. — JOHNSTON. 247 



There is no marked narrowing or lengthening at the posterior 

 end of the chain, the last segments being only a little longer and 

 slightly narrower than those further forward. 



The scolex is somewhat rounded, but its width is greater than 

 its length, that is if the rostellum be not included as it may be 

 retracted (PI. lxx., fig. 1.) Its size in this latter condition is 

 about 45 mm. broad by 031 mm. long. It is thus only a little 

 wider than the anterior segments. The retractile rostellum is 

 0T4 mm. long, its base being about O05 mm. in breadth, the 

 whole structure being short and conical. 



Near its apex, there is borne a single circlet of from thirty to 

 thirty-six hooks, all similar in shape and size, and measuring 

 about O05 mm. in length. They are so closely arranged that 

 there is difficulty in accurately determining their number, 

 arrangement and structural details. Their curvature is slight. 

 The apical attachment is long and apparently rather pointed, the 

 posterior attachment being short and blunt and rounded. The 

 free end is short and pointed. A cavity is present (PI. lxx , 

 fig. 2). The apices of the hooks do not reach the summit of the 

 rostellum. An apical muscle plug is absent. 



The scolex bears four typical suckers which are unarmed and 

 possess fairly prominent rims. The cavity of each is nearly 

 spherical, the internal diameter being almost Ol mm. The open- 

 ings are directed more towards the front than towards the sides. 

 Two suckers lie on each surface, i.e., two dorsal and two ventral. 

 Their musculature is well developed (PI. lxx., tig. 1). 



The cuticle is well defined and smooth. A basement mem- 

 brane is hardly distinguishable and sub-cuticular muscle fibres 

 are not well developed. The medulla occupies the middle third 

 of the thickness of the parenchyma. The cortex contains abun- 

 dance of calcareous corpuscles, especially in the neck region. 

 They are absent in the scolex. Their shape is rounded or 

 elliptical, the size varying from 0*003 to 0-008 mm. in diameter. 



The musculature of the cortex is strongly developed. The 

 longitudinal muscles are disposed in two concentric sets of 

 bundles, numbering about seventy altogether. The inner set 

 consists of smaller and fewer bundles than the outer. The inner 

 masses are generally opposite the outer, rather than alternating 

 with them. Laterally these muscles-bundles are very small and 

 numerous, being separated by the fibres of the transverse 

 muscles, which lie within the longitudinal but pass out laterally 

 to the cuticle. These transverse fibres are poorly developed so 

 that it is difficult to exactly define the limits of the cortex and 



