514 W. R. Coe — Anatomy of Cerehratulus laeteus. 



Figure 6. — Part of a radial cluster of ganglion-cells of the second type with fibres (/r^ 



passing to fibrous core of ventral lobe ; x 300. 

 Figure 7. — Ganglion-cells of the first (^c') and third types (gc^). The cell-walls are 



not readOy made out. Each cell is surrounded by a sheath of connective 



tissue, la, a single cell of the third type; x 300. 

 Figure 8. — Portion of a transverse section through the head to show the origin of the 



vagus nerves and their commissure (cv) ; d, cephalic lacuna ; cZ dorsal brain-lobe 



V, ventral brain-lobe ; x 12. 

 Figure 9. — Transverse section of Linens socialis through the region of the mouth ; «, 



nephridial canal in close relation with the lateral blood-vessel {Iv). On the left 



hand side is shown an efferent nephridial duct; o. mouth; Zc, lateral cord ; e, 



integument; c»2, circular muscles. From a small specimen ; x 40. 

 Figure 10. — Transverse section of a muscle-bundle. The nucleated fibres {mf) are 



each surrounded by connective tissue, and the muscle-bundle by a sheath (c) of the 



same tissue ; x 500. 

 Figure 11. — Transverse and longitudinal sections of muscle in Ca?-me?/a ; x 200. 

 Figure 12. — Transverse sections of three muscle-fibres from the anterior end of the 



proboscis-sheath. The flattened nucleus (n) is seen at one side of the contractile 



substance. But few nuclei are commonly seen: x 1000. 

 Figure 13. — Transverse section through the oesophagal region of Cerehratulus Leydii. 



The efferent nephridial duct {ue) joins the main nephridial canal near the lateral 



blood-vessel (Zy). Branches of this bloodvessel appear as large lacunae (oZ) sur- 

 rounding the oesophagus (oe); Ic. lateral cords; x 18. 

 Figure 14. — Transverse section through the anterior portion of the head of Valencinia 



to show the cephalic lacunae {cl) partially divided into many small spaces by 



thick strands of muscular tissue ; x 25. 



