No. 3-] THE ANATOMY OF NAUTILUS POMPILIUS. 151 



The tubules and the central cavity are lined by a columnar 

 epithelium. The epithelial cells are very slender, their height 

 being about twenty times the other diameters. Each cell con- 

 tains an oval nucleus situated near its base. 



The processes which contain the salivary glands are mainly 

 composed of connective tissue through which run strands of 

 longitudinal and longitudinally oblique muscle fibers. Blood 

 lacunae penetrate the process. Toward the upper end of it 

 the lacunae become so numerous that the connective tissue 



II 



10 



FIG. 3. Diagram of Nautilus pompilius, modified from Lang. i. Intestine. 2. Venous ap- 

 pendages. 3. Kidney chamber. 4,4. Gills. 5. Mantle. 6. Funnel. 7. Hood. 8. Shell-muscle. 

 9. Dorsal flap of mantle. 10. Crop. n. Gizzard. 12. Mouth. 



forms merely a network around them. The processes are 

 supplied with blood by an artery which comes from the buccal 

 branch of the anterior aorta. There is no closed capillary 

 system either in the salivary glands or in the processes. A 

 nerve from the buccal ganglion accompanies the artery. The 

 processes are clothed with a fine columnar epithelium. 



THE OTOCYST. 



The otocysts of Nautilus pompilius lie in hollows upon the 

 front side of the cartilage to which the great muscles of the 

 head and body are attached. They are situated one at each 

 side, below and behind the junction of the cephalic, pedal, and 

 pleural ganglia. The otocysts are ovate in form, and about 



