XI 



PHYLUM MOLLUSCA 



309 



and two auricles. An ink gland is present. In the latter, 

 on the other hand, the forefoot has the character of lobes 

 bearing tentacles ; the funnel does not form a complete 



FIG. 194. Oral surface of a male (A) and female (B) Nautilus pompilius in an 

 expanded state, J natural size, linear, a, shell; b, external annular lobe carry- 

 ing 19 tentacles on each side, and anteriorly enlarged to form the hood; c, right 

 and left inner lobes, each carrying 12 tentacles in the female, and divided in the 

 male into two parts; d, posterior inner lobe; e, oral cone; _/", tentacles of the 

 outer annular lobe projecting from their sheaths; g, two anterior tentacles of this 

 lobe belonging to the hood; /, superior, k, inferior, ophthalmic tentacle; /, eye; 

 , lamellated organ on the posterior inner lobe of the female; tn, paired lami- 

 nated organ on each side of the posterior inner lobe of the female; o\ funnel; 

 /, spadix; g, antispadix. (After Bourne, from Sedgwick.) 



tube. There is an external, chambered, spiral shell. There 

 are four ctenidia, four nephridia, and four auricles. The 

 ink gland is absent. 



