506 ALFRED GIBBS BOURNE. 



Tig. 65 (Plate XXXIl). — Pontobdella. Portion of a transverse section 

 passing through tlie excretory portion of the nephridium. nefh. apert. Tlie 

 aperture to the exterior, lined by cu. a cuticle. At x, the nephridial tubules 

 open into this invaginated portion, neph. Nephridial tubules. 



Fig. 66 (Plate XXXII). — Hirudo. Drawn from a transverse section by 

 Mr. W. E. Uoth, B.A., of Magdalen College, Oxford, d. v. Dorsal vessel, 

 containing shrunken blood-clot. g. Botryoidal tissue, al. ep. Alimentary epi- 

 thelium, m. Mucous droplets passing laio/d., the food-blood in the alimen- 

 tary canal. 



