138 



EXPLANATION OF PlyATE V. 



Fig. I. — General view of the animal from ventral surface. 



an. Anus. an. h. Anal hairs, c. Constriction, cr. Crop. 

 i. Intestine, m. Mouth, ce. (Esophagus ph. Pharynx. 

 pr. Prostomium. s^, s^, s^ First, second and third 

 bundles of setae, sg'^-''. Third to seventh body-seg- 

 ments, s. h, Sensory hairs on anterior part of body, 

 s/)'-^. Septa in the anterior part of body. st. Stomach. 



Fig. 2. — A seta. 



Fig. 3. — a-e. Diagrams illustrating asexual reproduction. 



Fig. 4. — Site of division. 



b.c. Buccal cavity, e.g. Cerebral ganglion, int. Intes- 

 tine of anterior animal, sph. g. Subpharyngeal ganglion. 

 Other letters as before ; all except int. have reference to 

 the posterior animal. 



Fig. 5. — Lateral view of the site of constriction, showing lateral 

 extension of nerve-cord in this situation. 

 int. Intestine, I.e. Lateral extension of nerve-cord. 

 v.n.c. Ventral nerve-cord. 



Fig. 6. — Growth of seta bundles near the site of a constriction. 



Fig. 7. — Lateral view of anterior part of body. 



b. cav. Buccal cavity, h. comm. Buccal commissure. 

 /. Fibres attaching pharynx to body- wall. n. First 



? nephridium. r. p. Refractile particle in the cerebral 

 ganglion, s. m. Setal muscle fibres, sp. Septum, show- 

 ing a projection due to a nucleus in its substance. 

 Other letters as before. 



Fig. 8. — Diagram illustrating chief blood-vessels. The arrows 

 show the direction of the contractions. 



Fig. 9. — Part of wall of crop, showing capillary blood-spaces 

 outside the crop epithelium. 



c. Capillary blood-space, n. Nucleus, ep. Epithelium 

 of crop. 



Fig. 10. — Diagram illustrating distribution of nephridia : parts of 



the aUmentary canal are outlined. 



w'-''. The nephridia. st'^. Stomach of anterior animal. 



pfi^j cs^, CY^ , sf^. Pharynx, oesophagus, crop, and sto- 

 mach of posterior animal. 

 Fig. II. — Anterior part of nerve-cord, seen from the ventral surface. 



is. Islands of nerve- tissue isolated from the rest. pj. 



Perforations along the median line of the subpharyngeal 



ganglion. Other letters as before. 



