7 
in the conformation of the head may be ascribed either to sexual dif¬ 
ference or to monstrosity. This must remain unsettled till another 
male can be observed; but I incline to the first opinion, a similar 
aberration of structure not having been observed in any of the hitherto 
dissected females. 
I have already described this male in a former paper*, but I be¬ 
lieve it will not be superfluous to give here the translation of the chief 
matter of my Dutch memoir on this specimen, together with some 
additional remarks and corrections. 
At the inner surface of the circle of digitations, which were eighteen 
at each side, without the hood, there was a prolongation of the inte¬ 
guments rising up to another more internal circle. This prolongation 
unites at the ventral side by a free and thin margin to the connecting 
basal part of the digitations. At the inner surface of this connexion 
of the external digitations, there are many transverse dimples parallel 
to the transverse margin of this commissure : many little holes give 
a reticulated appearance to this part. The prolongation becomes 
thicker and expands on each side in a processus divided in eight digi¬ 
tations of different size, including each a tentacle, similar to those 
contained in the external digitations of the head, but smaller, as usual 
in other specimens. On account of their place, those processes 
seemed first to me to be analogous to the superior labial processes of 
Prof. Owen’s memoir, because they are situated at the dorsal side, and 
consequently I described them under that name in my former publi¬ 
cation ; 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 supe¬ 
rior position. The fold of the integuments connecting those pro¬ 
cesses at the central side to another in the mesial line divides in two 
plates ; the exterior adhering to the commissure of the external digi¬ 
tations already described; the interior miited 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 hi 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 Prof. 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 out¬ 
wards to them a fold in the inner surface of the external circle of di¬ 
gitations. At the right side a processus is exserted from this fold; 
* Tijdschrift voor de natuurkundige Wetenschappen, uitgegev. door de eerste 
Kl. v. h. Koninkl.-Nederh Instit. i. 1848, p. 67-75. A short abstract of this de¬ 
scription was communicated by me at the Oxford Meeting (1847) of the British 
Association, and is inserted in the Report of the Seventeenth Meeting of the 
British Association; London, 1848 ; Transactions of the Sections, p. 77. 
