ARGONAUT A. 



Plate IV. 



Species 3. (Fig. a, b, Mus. Cuming.) 



Argonauta gondola. Arg. testa semiorbiculari-invo- 

 lutd, late inflatd, lateribua convexis, rugis validis, ob- 

 liquis, pauciusculis, lavibus, alternis brevioribus ; ca- 

 rina latiusculd, tuberculin amplis, distantibus ; auri- 

 culis exterius prolongates. 

 The gondola Argonaut. Shell semiorbicularly invo- 

 lute, broadly inflated, sides convex, wrinkles strong, 

 oblique, rather few, smooth, the alternate ones 

 shorter ; keel rather broad, tubercles large, distant ; 

 auricles prolonged outwardly. 

 Dillwvn, Desc. Cat. of Shells, vol. i. p. 335. 



Argonauta Kochiauus, Dunker. 

 Hab. South Atlantic Ocean ; Belcher. Philippines; Cu- 

 ming. 

 This largely tubercled widely gaping species is fre- 

 quently taken for A. Mans, but the species are distinct, 

 and this is the more gaping of the two. The auricles are 

 sometimes expanded and twisted outwardly into lateral 

 horns, but, as may be seen by the specimens of A. gondola 

 figured, no reliance can be placed on this as a specific cha- 

 racter. In that given at Fig. 3 a, the auricles are not 

 horned at all, whilst in that given at Fig. 3 b, they are 

 horned conspicuously. The same differences may be ob- 

 served in specimens of A. tuberculosa. 



The auricles of the Argonaut shell are the most variable 

 part of its structure, depending, doubtless, very much in 

 their formation and growth on the overlapping of the ten- 

 tacles of the animal. 



Species 4. (Mus. Cuming.) 



Argonauta hians. Arg. testa semiorbiculari-involutd, 

 nitente-fidvd, lateribua modice convexis, rugis lumidius- 

 culis, vix uudulatis, alteruatim brevioribus; carina lata, 

 tuberculis amplis, distantibus ; auriculis simpliciius. 



The gaping Argonaut. Shell semiorbicularly invo- 

 lute, shining fulvous, sides moderately convex, wrin- 

 kles rather swollen, scarcely waved, alternately shorter; 

 keel broad, tubercles large, distant ; auricles simple. 



Dillwyn, Desc. Cat. of Shells, vol. i. p. 334. 



Argonauta nitida, Lamarck. 



Argonauta raricosta, De Blainville. 

 Ocythoe Cranchii, Leach. 



Hab. South Atlantic Ocean ; Belcher. 



The wrinkles are more faintly developed in this species 

 than in the preceding, the keel is not so broad, and the 

 tubercles are less prominent. The shell has, moreover, a 

 fulvous, glazy appearance, which probably suggested the 

 name of nitida, given to it by Lamarck. The Argonaut, 

 animal and shell, described and figured under the name of 

 Ocythoe Cranchii by Dr. Leaeh, in the ' Philosophical 

 Transactions of the Royal Society' for 1817, from speci- 

 mens collected by Mr. Cranch, in the Gulf of Guinea, is 

 so immature in growth that it is not possible to decide 

 with certainty whether it is the young of this or of the 

 preceding species. 



Species 5. (Mus. Cuming.) 



Argonauta Owenii. Arg. testa semiorbiculari-involutd, 

 nitente-fulvd, lateribus convexo-compressis, rugis pro- 

 minentibus, uudulatis, alteruatim brevioribus; carina 

 mediocri, conspicue tuberculatis, tuberculis numerosis ; 

 auriculis simplicibus. 



Owen's Argonaut. Shell semiorbicularly involute, 

 shining fulvous, sides convexly compressed, wrinkles 

 prominent, waved, alternately shorter ; keel middling, 

 conspicuously tubercled, tubercles numerous ; auricle* 

 simple. 



Adams and Peeve, Moll. Voy. Samarang, p. 4. pi. 3. 

 f. 2 a to d. 



Hab. South Atlantic Oceau ; Belcher. Moreton Bay, 

 Australia ; Strange. Philippines ; Cuming. 



The differences between adult specimens of this and the 

 preceding species are not very perceptible, excepting that 

 in A. Owenii the sides are more flatly compressed, and the 

 aperture is consequently less gaping. But in an earlier 

 stage of growth, as represented by the suite of specimens 

 figured in the ' Mollusca of the Voyage of the Samarang,' 

 it will be seen that the wrinkles are closer and more con- 

 spicuously developed, and the tubercles in which they ter- 

 minate on the edges of the keel are consequently stronger 

 and more numerous. ' Mr. Cuming possesses specimens 

 in this state collected by Mr. Strange, at Moreton Bay, 

 Australia, and by himself at the Philippine Islands. 



April, 1861. 



