OF NAUTILUS POMPILIUS. 27 



publication ; but as they are internal or nearer to the mandibles than the other pair of 

 similar processes, I now believe them to be analogous to the inferior labial processes in 

 the female, notwithstanding their superior position. The fold of the integuments con- 

 necting those processes at the central side to another in the mesial line divides in two 

 plates ; the exterior adhering to the commissure of the external digitations already 

 described ; the interior united to the covering of the mandibles. Between those two 

 plates a pair of depressed cushion-like parts is placed, coming in contact to another in 

 the middle, and nearly wholly adherent at their inferior surface to the inner plate. 

 They have nearly 8 lines in length and 4^ in breadth. Their free, superior and internal 

 margin is divided by incisions in ten or eleven small tetragonal parts ; the right 

 part having eleven, the left ten of those digitations. The relative position seems to 

 prove them to be analogous to the folds between the internal labial processes, which 

 are considered as the olfactory apparatus by Professor Owen. I believe they afford an 

 additional argument against this opinion, because they are doubtless only rudimental 

 digitations. 



Beneath those internal labial processes there is at each side outwards to them a fold 

 in the inner surface of the external circle of digitations. At the right side a processus 

 is exserted from this fold ; it consists of the conjunction of the sheaths of four tentacles ; 

 three of those tentacles are placed on a common fiat expansion ; the fourth is contained 

 in a separate slip, placed beneath the three other tentacles. At the left side, instead of 

 this external labial processus, there was a great conoid body, the length of which was 

 nearly 2^ inches ; this part was laterally compressed ; at the basis its measure from the 

 dorsal to the ventral side was found to be 1 inch 10 lines ; from the right to the left 

 side only 1 inch. This part was proved to me by dissecting it to be formed by the 

 union of four unusually developed tentacular slips, one of which was shorter and more 

 free, the three other chiefly composing the singular body. This part occupied a great 

 space in the interior of the circle, which was formed by the external tentaculiferous digi- 

 tations of the head, and perhaps its great development may have been the cause of the 

 more imperfect condition of the other three labial processes. 



I regret that this specimen was in a bad state of preservation ; its abdominal sac 

 being dilacerated and the viscera destroyed by maceration. Hence I am not able to 

 give a description of the male organs of generation, but that the specimen was a male 

 seems to me unquestionable. At the same place where in other specimens the vulva 

 adheres to the ground of the branchial cavity, was a short conic part, evidently the 

 penis, somewhat bent at the basis towards the ventral side, having an obtuse and perfo- 

 rated top. A very narrow canal was found to go from this aperture to the root of the 

 penis, and to expand there in a pouch, of a firm parchment-like texture. This bladder 

 contained a conglobate tube of a brown colour, having a little more than 1 line in dia- 

 meter. The length of this tube could not be determined, because, by any attempt to 

 unravel it, it broke into pieces. Microscopic investigation proved that this tube was 



