ARGONAUTA. 



Plate I. 



Genus AEGONAUTA, Linnceus. 



Testa navicularis, bicarinala, unilocirfaris, tenuis, papyra- 

 cea, minute granulata, spird discoided, in aperturam 

 involute immersd, alba, fusco-favescente sape tincta, 

 carina versus spirant plus minus f umeo-nigricante ; la- 

 teribus radiaiim rugatis, rugis vel continuis vel noda- 

 tis, ad carinam in luberculis plus minus conspicue mu- 

 ricalo-squamatis desinentibus. 



Shell ship-shaped, double-keeled, one-chambered, thin, 

 papyraceous, minutely granulated, spire discoid, in- 

 volutely immersed in the aperture, white, often tinged 

 with fuscous-yellow, keel smoky-black towards the 

 spire ; sides radiately wrinkled, wrinkles either con- 

 tinuous or noduled, terminating at the edges of the 

 keel in more or less conspicuously prickly-scaled tu- 

 bercles. 



The shells of this genus being merely the egg-cradles 

 of a Cuttle-fish, constructed only by the female for the 

 purposes of oviposition, great inconvenience has arisen 

 through naming them in the absence of the animal. Up 

 to the present century the octopod or eight-legged Cuttle, 

 one of the Polyps of Aristotle, usually found in these 

 shells, was thought to be a parasite. But no one had 

 determined the question. The shell was simply called by 

 the early conchologists Ovum Polypi and Domuncnla Po- 

 lypi. Linnasus established the genus Argonauta for its 

 reception, and it became known generally by the appella- 

 tion of the Paper Nautilus. In 1817 some young speci- 

 mens of the animal and shell, captured in the Gulf of 

 Guinea by Mr. John Cranch, zoologist of the unfortunate 

 Congo Expedition, were placed in the hands of Dr. Leach, 

 of the British Museum. Convinced that the animal was 

 no parasite, he described it in the ' Philosophical Transac- 

 tions of the Royal Society ' of that year as a new genus, 

 Ocythoe, and his paper was accompanied by an engraving 

 of a specimen in six different positions. The author was, 

 however, mistaken in supposing that the parasitic nature 

 attributed to the animal usually found in the Paper Nau- 

 tilus had not been disproved. The calcifying functions of 

 the hinder pair of legs, which become modified in the fe- 

 male into a pair of membranous webs, secreting the shell, 

 had been well established by Cuvier in the ' Dictionnaire 

 des Sciences Naturelles' of Paris, thirteen years before. 

 The observations of Dr. Leach served, however, to revive 

 an interest in the subject, and they have been followed by 



a series of most interesting experiments and researches on 

 the part of M. Eang, MM. Ferussae and D'Orbigny, M. 

 Rafinesque, Madame Power, Professor Owen, and Mr. 

 Arthur Adams. About twenty years since I had myself 

 above a thousand specimens of A. Argo, many with their 

 animals in spirits, placed in my hands by the Rev. L. B. 

 Larking, who collected them during a temporary residence 

 at Messina ; and the specimens collected by Sir Edward 

 Belcher and Mr. Arthur Adams during the voyage of the 

 Samarang, afforded me further means of examination. 

 " On our passage home across the South Atlantic," writes 

 Mr. Arthur Adams, " I enjoyed numerous opportunities 

 of observing the animals of A. 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. 

 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 num- 

 ber of instances, being found embracing their calcareous 

 shell-nests." 



One of the most conspicuous features in the natural his- 

 tory of the Argonauts is their wide geographical distribu- 

 tion. A. Argo appears to range within an area of forty 

 degrees on either side of the Equator in both hemispheres. 

 The Mediterranean and the Indian, South Atlantic, and 

 Pacific Oceans, are all recorded as habitats under our de- 

 scription of this species ; and A. tuberculosa is recorded 

 from the Moluccas, from Tasmania, and from Brazil. Se- 

 veral more species have been described than can, I think, 

 on further research, be admitted. The seven enumerated 

 by De Ferussae and De Blainville are reducible to four ; 

 and six are the most that can even now be satisfactorily 

 determined. 



Species 1. (Mus. Cuming.) 



Argonauta tuberculosa. Arg. testa orbiculari-invo- 

 lutd, ventricosiusculu, lateribus convexis, rugis undique 

 nodoso-tuberculatis ; carina lata, tuberculis prominen- 

 tibus, subdistantibus ; auriculis contraclis, interdum 

 calloso-prolongatis. 



The tubercled Argon.aut. Shell orbicularly involute, 

 rather ventricose, sides convex, with the wrinkles no- 

 dosely tubercled throughout; keel broad, with the 



April, 1861. 



