SOME NEW AND RARE CEPHALOPODA. 113 
the Argonaut ; there are fifteen pairs in each gill. The peritonewm, or external mem- 
brane of the viscera, was remarkably mottled with large purple-red spots: I have ob- 
served the same disposition of a brown pigment on the peritoneum in the Argonauta'. 
The pigment which gave the purplish tint to the skin when the animal was alive, 
appeared to have been driven from the surface; for on removing the cuticle, which was 
remarkably thick and elastic in this small Cephalopod, only some small brown spots 
were perceptible in the vesicular rete mucosum : these were aggregated chiefly on the 
dorsal aspect of the body and head. 
As the generative organs were scarcely developed in either of the specimens, it is 
probable that they may not have arrived at maturity, and the species consequently may 
be assumed to attain a greater size than that of the largest individual in the collection, 
which measures only 1+ inch from the bottom of the sac to the extremity of the longest 
arm. ‘The prominence of the eyes, the structure of the funnel, the proportions of the 
arms, and the partial development of the interbrachial web, will however afford the 
means of distinguishing this species when it is again met with. 
The very interesting specimen cf the Paper Nautilus, or Argonaut, which forms part 
of Mr. Bennett’s collection of Cephalopoda, is thus noted in his journal :— 
“‘March 7th. Fine weather ; light and moderate south-east trade breezes; therm. 
from 81 to 84; lat. 4° 43' south, long. 17° 37' west. I did not capture a singlé spe- 
cimen with the net during the day ; but at 8 p. m. I procured some small specimens of 
Exocetus, and also an excellent specimen of an Argonauta: on placing it in sea-water it 
expanded its tentacula, but did not attach itself to the glass, or move about. Early on 
the following morning I found the animal dead in the glass of sea-water in which I had 
placed it on the previous night, and on moving the shell to take it out, the soft parts fell 
out. After the animal was out of the shell, a cluster of ova was seen attached to the in- 
voluted part of the shell ; somewhat resembling, but in the recent state more beautifully 
shown than in, the engraving of apparently a similar specimen in the Appendix to 
‘Tuckey’s Narrative of the Congo Expedition.’ On placing the shell in spirits, the 
cluster of ova floated out like a diminutive plant of a pure white colour, presenting a very 
elegant appeararice. After being preserved a day in spirits, much of this beautiful ap- 
pearance was lost. The body of the animal was of a dark reddish colour, which colour 
was also given to the upper part of the shell, either naturally or imparted to it by the 
animal ; the remainder of the animal was of a dirty white with minute purplish dots ; 
and the arms were also speckled underneath of a similar colour : the suckers were white. 
These cephalopodous animals are not (and I consider correctly) regarded as the true 
inhabitants of the shell, but merely parasitical inhabitants ; and the animal not having 
* A development of pigment on the serous membrane of the abdomen is observable in many fishes, and in 
some reptiles, as Anguis fragilis, Ophisarus ventralis, and some species of Lacerta, Cuy., and in Agama atra, 
where the peritoneal pigment is almost black. 
Q2 
