PLATE XXII. 



Fig. 



1. Transverse section of the cephalic ganglia of Linens gesserensis. The pale central 



portions are caused by the imperfect penetration of the fluid in mounting. X 210 diam. 



2. Transverse section of the curious variety of Carinella from Balta. d, external layer of cutis ; 



d\ basement-layer; e, longitudinal muscular layer; [e a, dorsal subdivisions of the latter 

 coat in the central line ; e', circular muscular coat ; j, section of the oesophageal region of 

 the digestive tract; j a, distinct band of muscular fibres enclosing the latter; n } lateral 

 nerve; o, sheath for proboscis; r y vascular spaces. X 55 diam. 



3. Transverse section of the postganglionic region of Lineus lacteus, showing the long vascular 



lacunae (s, s) in front of the oesophageal region. The slice of the proboscis has fallen out 

 of its sheath (o). X 90 diam. 



4. Anterior 'end of a contracted specimen of L. gesserensis, turned round so as to exhibit 



the marked separation between the oesophageal region and the digestive cavity proper. 

 X 90 diam. 



5. Adventitious granular mass {a) in a longitudinal section of the dermal tissues of Lineus 



marinus. b, b, spaces from which similar structures have fallen. Other letters as in pre- 

 vious figures. X 210 diam. 



6. Aggregations of fatty granules from the discarded coating of the embryo of Lineus gesserensis. 



X 210 diam. 



7. Anterior end of a fragment of Lineus sanguineus, about three weeks after rupture, a, terminal 



aperture; d, cutaneous layers. X about 40 diam. 



8. Posterior end of the same fragment, similarly magnified, z, anus. 



9. Anterior portion of a fragment in a more advanced condition, a, developing proboscis ; 



h, indication of ganglia. 



10. Anterior region of a complete, or nearly complete, animal developed from a fragment; 



j, oesophageal division of the alimentary canal; m % cephalic pit and sac ; w, mouth. 



11. View of a similar specimen; the regenerated anterior portion, consisting of the head and 



the oesophageal region of the digestive chamber, is recognized by its pallor ; b, cephalic 

 fissure. Magnified under a lens. 



