36 



Fig-, fi. Lonoitiulinal hoiizoiital section throug-h intes- 

 tinal region, shewing the intestinal divertirnla 

 alternating with the gonads. x 45. 



Fig. 7. Flask-shaped egg capsule, containing a single 

 embrvo in the inornla stage. (After M'Intosh.) 

 X 25. 



F'ig. 8. Transverse section through intestinal region 

 passing between two diverticula. x 45. 



Plate IV. 



Fig. 1. Schem'atic figure, shewing ihe relations of the 

 various systems in the anterior end of the 

 animal as vieAved from above. The proboscis 

 and its sheath, the oesophageal nerves and the 

 buccal vessels have been omitted. 



Fig. 2. Transverse section through lateral blood vessel. 

 On the side of the alimentary canal the paren- 

 chyma cells are smaller and complete. On the 

 outer side no cell wall is to be distinguished 

 away from the vessel. x KiS. 



Fig. '■). Portion of oesophageal epithelium fiom a trans- 

 verse section. Three kinds of gland cells are 

 seen among the ciliated epithelium and below 

 it: — (a), (S), and (h. (for explanation vide 

 text). X 168. 



F'ig'. 4. Two s])ermatozoa (aftei' MTntosh). x 700. 



Fig. 5. Larva of ])esor as seen from the ventral surface. 

 The outer ciliated coat is not yet slied. (After 

 Barrois). 



Fig. n. Young Linens just hatciied. x 40. (After 

 M'Intosh). 



F^igs. 7-lL Diagrammatic sections through larvjB of 

 Lineus at different stages. (After Hubrecht). 



