No. 3.] THE ANATOMY OF NAUTILUS POMPILIUS. 149 







Upon examining a large series of shells (more than one 

 hundred) and the sixty-six specimens of Nautilus in the collec- 

 tion, I found that the dorsal and posterior ventral aponeurotic 

 bands limit the formation of the septa. The entire area of 

 the mantle posterior to these bands is active in the secretion 

 of the lime forming the septa. But at the boundary formed 

 by these bands the formation ceases. As the animal grows 

 away from the last-formed septum the bands also move for- 

 ward, maintaining a constant relation to the shell-muscles. A 

 slight deposition of lime upon the inside of the shell extends 

 forward from the edge of the septum to the above-mentioned 

 limiting bands. It is evident that during what are called the 

 resting periods of the Nautilus an intense secretory activity 

 is maintained (at least in certain areas), and that during grow- 

 ing periods the secretion is very slight. 



THE SALIVARY GLANDS. 



The presence of salivary glands in Nautilus has been con- 

 sidered doubtful. Near the oesophagus, upon the floor of the 

 mouth, are two papillose processes, one at each side of the 

 tongue. Owen ('32) described these as containing glandular 

 cavities. Valenciennes ('41) more correctly described glan- 

 dular bodies within the processes. From studies made upon 

 serial sections of these glands I am convinced that they are 

 true salivary glands, homologous, at least, with the anterior 

 salivary glands of the Octopoda. 



The glands are ovoid in shape, situated within the lower third 

 of the processes. As a rule, each process contains but one 

 gland ; in one case, in which serial sections were made of the 

 process, an accessory gland was found opening beside the main 

 gland. The glands are compound tubular, all the tubules 

 being separated by septa of connective tissue which extend in 

 from the body of the process, and all opening into a common 

 central cavity. In some cases this cavity opens into the 

 mouth cavity directly, while in others a very short duct leads 

 from the gland to the mouth cavity. The opening of the duct 

 into the mouth is upon the inner side of the process, somewhat 

 below the center. 



