140 T. H. JOHNSTON. 



segment is 0*225 mm., its greatest width (excluding the 

 suckers) being 0*187 mm., or 0*226 mm. if we include them. 

 The width at its posterior end is only 0*072 mm. 



The rostellum is distinct but short, merely forming the 

 anterior corner of the rhomb. On its apex there is present 

 a more deeply staining disc resembling the apical or 

 rostellar musculature of some other tapeworms, and to it 

 are attached the circlet of hooks. In its centre there is a 

 shallow rounded depression which lends to the opinion that 

 the rostellum is retractile. The organ is not sucker-like. 

 The hooks are arranged in a single circlet of about fourteen. 

 They are comparatively long, thin and prominent, measur- 

 ing about forty millimetres in total length. The anterior 

 attachment or handle is rather pointed at its free end and 

 only gradually widens towards the guard. It is fairly long 

 (11/*). Its shape is seen in Plate 8, fig. 3. The guard is 

 rather prominent and is regularly rounded. The shaft is 

 by far the longest part of the hook, reaching a length of 

 nearly thirty micra. There is a gradual narrowing until a 

 delicate strongly-incurved extremity is produced. 



The four suckers are distinctly projecting, muscular, 

 unarmed organs arranged as a pair on each flat surface. 

 There is only a narrow but comparatively deep depression 

 between each pair. The apertures are directed antero- 

 lateral^ and measure nearly 0*1 mm. in diameter. The 

 surrounding muscular rim is prominent. 



Strobila :— The head becomes narrowed posteriorly to 

 join the segmented part of the strobila. There is no unseg- 

 mented neck region, the proglottids commencing immedi- 

 ately behind the scolex. The segments alter considerably 

 in shape and size in different parts of the chain. The first 

 few are many times broader than long; beyond this the 

 segments gradually lengthen into a shape resembling a 

 short bell, the posterior edge of each overlapping the anterior 



