MOLLUSCA. o 



to attach an interesting importance to several examples of this species in an early stage of 



growth, which were captured alive, but unfortunately dried up from an accident in the 



packing. It is mainly distinguished by the prominent structure of the lateral wrinkles and 



tubercles, and these are developed with equal force in the youngest specimens. It is clearly 



distinct from A. Mans, for the young of which species a small specimen was figured by 



De Ferussac and D'Orbigny in their great work on the Cephalopods, Hist. Nat. Moll., 



published in 1837. In naming this shell we have availed ourselves of the rare occurrence of 



a new species to dedicate it to Professor Owen. 



Plate III. Fig. 1 a. Front view of the shell, showing the aperture and simple auricles. Fig. 1 b, c, and d, 

 lateral views of specimens of different ages. 



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, Hyalma, Firola, and Cleodora. My observations all tend to prove, as might have 

 been expected, the accuracy of Madame Power's observations on the Cephalopodic origin of the shell, and 

 the fanciful nature of the statements of Pliny, Poli, and the poets. 



It is quite true that the female Argonaut can readily disengage herself from the shell, when the vela- 

 mentous arms become collapsed, and float apparently useless on each side of the animal ; and it is equally 

 certain that she has not the power or, more properly, the sagacity to re-enter her nest and resume the 

 guardianship of her eggs. On the contrary, she herself, if kept in confinement, after darting and wounding 

 herself against the sides of the vessel in which she is confined, soon becomes languid, exhausted, and very 

 shortly dies. Numbers of male Argonauts were taken by us, at the same time, without any shells, and this 

 being the season of oviposition may account for the females, in such a number of instances, being found 

 embracing their calcareous shell-nests, which, so ingeniously formed by the instinct of the mother for the 

 protection of her eggs from injury, resemble, in some measure, those nidimental capsules secreted by 

 many marine Gastropods for the preservation of the immature embryo. 



To satisfy myself that the thin shell of the Argonaut is employed by the female merely as a receptacle 

 in which to deposit her eggs, I dissected a specimen of A. gondola, with an egg-mass occupying the dis- 

 coidal part of the shell and the posterior portion of the roof. The eggs, very numerous, ovoid, pale yellow, and 

 semipellucid, are all united together by a delicate, glutinous, transparent, filamentous web which is attached 

 to each ovum by a slender tapering peduncle at the anterior extremity. The entire egg-mass is suspended 

 to the body-whorl of the spire at its anterior part by means of a pencil of delicate glutinous threads which 

 retain it in a proper position. 1 



The posterior globular part of the body of the female is in close apposition to the mass of ova, and 

 thus, like a strange aquatic Mygale, or other spider, does this remarkable Cephalopod carry about her eggs 

 in a light calcareous nest, which she firmly retains possession of by means of the broad, expanded, delicate 

 membranes of the posterior pair of tentacles. When disturbed or captured, however, she loosens her hold, 

 and leaving her cradle to its fate, swims about independent of her shell. 3 There is not, indeed, the slightest 



1 Poli in his magnificent work " Testacea utriusque Sieiliaj," where he has represented the egg-mass, though not 

 " in situ " (Tab. XLI. f. 2.) but unravelled, observes concerning it : " Ovorum congeries eboris nitorem asmulantiuni, 

 partim jam ab ovario emissa, ac racemorum instar composita, cymba? puppi involuta? adhasrebat. " Professor Owen, 

 in his lectures on Comparative Anatomy, p. 360, mentions the same fact : "In the Argonaut the minute ova are 

 appended by long filamentary stalks to the cavity of the involuted spire of the shell where they are hatched." 



2 This is probably but for a limited period, as it does not appear that the animal is able to exist long when 

 disengaged from its shell. 



C 



