32 THE SHELL. 



accumulated. The want of attachment of the animal by adductor 

 muscles, and the fact that the shell itself is not moulded on the 

 animal's body, and does not correspond to its shape were con- 

 sidered such strong evidence of parasitism, that the animal 

 itself was described as Ocythoe, and the shell as Argonauta. 

 The observations of Madame Jeanette Power first set this vexed 

 question at rest, by showing that the animal builds its shell by 

 the exudation of material from the expanded or velamentous 

 arms of the female, instead of from the mantle, as in true shells. 



The Argonaut shell, or egg-hest, is structurally composed of 

 small plates or prisms ; its earlier portion is covered with a 

 chagrined cuticle, and its toothed periphery is stained with 

 brown. On either side the velamentous dorsal arms are applied 

 to its external surface, and not onl}'^ do they add to the margin 

 when growth takes place, but they suffice also to renew any 

 broken portion of the already existing walls. 



In a specimen of Argonauta argo, which forms a part of the 

 collection of Amherst College, a portion has been broken out 

 near the middle of the left side, and not far from the sinus of the 

 aperture. A new deposit of testaceous substance, together with 

 a broken fragment, has closed the opening in the rude manner 

 common in the shells of the mollusca. But the most extraor- 

 dinary circumstance is that a fragment which was broken out in 

 the accident which befell the animal, now constitutes two-thirds 

 of the repaired portion, and that the original inner surface is now 

 the outer surface, as is evident from its concavity, style of 

 undulation, and texture. It is also nearly at right-angles to its 

 original position. These facts show that the piece was totally 

 detached from the shell by the accident. The vela of the Argo- 

 naiTt, by clasping and enveloping the shell, had evidentl}^ 

 prevented the loss of this fragment. It is obvious, also, that the 

 new deposit of testaceous matter was secreted from the part of 

 the animal within the shell, and not from the vela, since the 

 edges of the original shell around the fracture appear exclusively 

 on the outside. — G. B. Adams, A7n. Jour. Sci,, 2 ser., vi, 138, 

 1848. 



Madame Power has seen the fractured shell of an Argonaut 

 partially repaired by membrane in less than six hours. 



The subjoined notes of an accurate modern naturalist afford 

 conclusive evidence of the non-parasitism of the Argonaut. 



On our passage home across the South Atlantic, I enjoyed 

 numerous opportunities of observing the animals of Argonauta 

 argo and gondola in the living state, specimens having been 

 captured by us in large numbers by means of a trawl, as they 

 came to the surface of the water at the decline of day in calm 

 weather, in company with Carinaria, Hyalsea, Firola and Cleo- 



