THE NAUTILUS. 



29. 



Sta — Statocyst In S — Incurrent siphon 



V —Ventricle G —Gill 



Au — Auricle Man — Mantle 



PI — Pericardium Shi — Shell 



Kd — Kidney 



Figure 2. Cross section of egg-bearing follicle of Calyculina. 

 0 — Egg Ep — Epithelium 



Bt — Basement membrane Yo — Young egg 



Figure 3. Cross section of sperm-bearing follicle. 

 Sp Mc — sperm mother cells. Sp — sperm 



Figure 8. Frontal section of inner gill of Calyculina show- 

 ing brood pouch. Drawn with Edinger machine. 



0 L 



— Outer lamella 



Ct 



— Cross threads 



I L 



— Inner lamella 



Em 



— Embryo 



a 



—Cilia 



Sh 



— Shell remains 



G Fil 



— Gill filament 



CI Ch 



— Cloacal chamber 



Bs 



— Blood space 



Gc 



— Gland cells of inner 



I W 



— Inner wall of brood 





wall. 





pouch 



Sec 



— Secretion 



0 w 



— Outer wall of brood 

 pouch 







Plate V. Figure 4. Diagrammatic section of 

 Calyculina. 



T — Sperm follicles Gd — Genital duct 



Or — Egg follicle G 0 — Genital opening. 



Figure 5. Diagrammatic cross section through the region of 



the reproductive organs. Calyculina. 



Pp — Pericardium M — Mantle 



V — Ventricle Ft — Foot 



An — Auricle CI Ch — Cloacal chamber 



Bs — Blood space 0 — Egg follicle 



R —Rectum T — Sperm follicles 



I G — Inner Gill Nc — Nerve cords 



0 G —Outer Gill C T —Connective tissue 



