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 43 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 flat 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 
