196 



Records of the Indian Museum. 



[Vol. X, 



The inner and outer cuticular layers completely enclose the 

 muscular layer, becoming continuous with one another at the 

 mouth of the cup and at the perforation at the base The fibres of 

 the muscular layer radiate from the centre of the sucker cup, in 

 such a manner that when they contract (acting from the outer 

 cuticular layer as a fixed surface) they enlarge the cavity of the 

 cup and thereby produce a vacuum. This action is aided by the re- 

 tractor muscles attached to the perforation. 



The cotylophore bears two pairs of hooks situated between 

 the posterior pair of suckers (PI. xxvi, fig. i). One pair is large 

 and sabre-shaped, 0*9 mm. in length, the points curved boldly for- 

 ward (h.i.). Plate xxix, fig. 18 exhibits the base of such a hook in 

 transverse section. The hooks of the second pair are short, o- 166 

 mm. in length, fine and simply curved (PI. xxvi, fig. 1, h.2). 



Ani. 



Tost. 



Fig. I.— The circlet of atrial hooks as seen from the ventral surface, X f)5u. 



Alimentary System. — The flattened mouth leads into the first 

 pharynx — a spherical muscular bulb (PI. xxvi, fig. i. PI. xxvii, 

 2, 3, and 4, ph.i) which possesses walls of great thickness and 

 a comparatively narrow lumen. The second pharynx (PI. xxvi, 

 fig. I. PI. xxvii, 5 and 6, ph. 2) is identical in shape with the 

 first, and lies dorsal and posterior to it. From the second pharynx 

 a narrow, short and muscular oesophagus leads into the intestine 

 (PL xxvi, fig. I. xxviii, 7, 8. xxix, 14, 17. int.) an organ of the 

 customary two-limbed type. The limbs are unbranched and devoid 

 of anastomoses. They extend backward into the region of the 

 cotylophore. 



The Skin. — The ectoderm exhibits structure only in a few 

 sections (PI. xxvii, fig. 5). In these it appears to consist of a high 

 palisade like epithelium. Nuclei are not visible except in the 



