64 CONTRIBUTIONS TO AMERICAN HELMINTHOLOGFY, 



The general outline of the body is somewhat oblong when the woriK 

 is at rest; in motion, however, its form is capable of considerable 

 variation, and it is especially then that the constriction corresponding 

 to the position of Zeller's " Seitenwiilste " is noticeable. The caudal 

 lamina is somewhat narrower than the greatest width of the body, 

 and is shorter than it is broad. The body narrows considerably at 

 its junction with the caudal lamina. 



The hooks and suckers are disposed very much as in P. integerri- 

 mum. The suckers (0.2 mm. in diameter) seem to project rather 

 more than in that species, and their prominent rim bears a series of 

 rounded apertures similar to those spoken of above in describing the 

 suckers of Octobothrium sagittatum. The smaller hooks (Fig. 11) 

 measure 0.015 mm. in length. The six anterior of these are situated 

 in pairs between the two anterior suckers. They have a knobbed 

 attached end, with an arm (long-er than represented in the figure) pro- 

 jecting at right angles not far from the middle of the hook. The four 

 posterior (situated between the larger hooks) are capable of more 

 independent action than the others. This was evident when the 

 worm endeavoured to free itself from the piece of thin glass by which 

 it was covered. The two large hooks measure 0.15 mm., and have a 

 proportionately deeper notch than those of P. integerrimum.^^ 



No eye-spots were observed iir the adult worm. The longitudinal 

 system of muscular fibres seemed to be most developed. 



The mouth is transversely oval, and is surrounded by a well-marked 

 sucker, in which radial and vertical fibres preponderate. It leads 

 immediately into a bowl-shaped pharynx, the walls of which possess 

 merely weak circular fibres, and from this the simple intestinal coeca 

 arch backwards directly. The coeca of all the observed specimens 

 were empty. 



Only the convoluted lateral stems of the water-vascular system 

 were observed near the anterior end. 



The lobes of the viteUogen are more scattered than in P. integerri- 

 mum, and do not extend into the caudal lamina. The transverse 

 duct seemed to pass inwards dorsally from the intestinal coeca ; but I 

 have been unable to determine the relationship of the internal genera- 

 tive organs, partly from the fact that my specimens were taken from 

 the turtle the day after it was killed, and conseqtxently had very little 

 vitality. 



22 Cf. Zeller, loc. cit., Taf. XYII. p. 12. 



