104 Dr. E. von Martens on the Species of Argonauta. 



D'Orbigny limits himself to the same three species, admitting 

 A. gondola and haustrum, Dill., as varieties oi A. tuberculata and 

 Argo. Reeve, in the 'Conchologia Iconica,^ vol. xii. 1861, 

 admits five species ; H. and A. Adams, in the 'Genera of Mol- 

 luscous Animals,' 1858, and Sowerby, in the ' Thesaurus Conchy- 

 liorum,^ six species. 



On reviewing the twenty-nine specimens exposed in the Ber- 

 lin Museum, I was impressed with the conviction that they all 

 are referable to three constant types : — 



1. Type oiA.Argo: ribs smooth and numerous; keel nar- 

 row ; colour white. 



2. Type of A. tuberculata, Shaw {nodosa, Solander, tvhercu- 

 Zosfl, Lam., oryzata, Meuschen) : ribs tuberculated, numerous; 

 keel rather narrow ; colour white or pale yellow. 



3. Type of A. hians, Solander {nitida. Lam.) : ribs smooth, 

 distant, and therefore few ; keel broad ; colour yellowish or light 

 brown. 



In all three the hinder part of the keel is very often tinged 

 with dark brown ; this dark-brown colour is wanting in a few 

 specimens of A. Argo and tuberculata, and in many of A. Mans. 



Within each of these types there are specimens in which the 

 lateral edge of the apertui-e is nearly straight, the aperture 

 therefore narrow (forma mutica), and others in which this edge 

 forms near its inner end an angle which is more or less blunt 

 (forma obtusangula), or extends itself into a prolongation called 

 the ear (forma aurita). 



Type of Argonauta Argo : — 



a. Forma mutica : A. Gruneri (Dunker), Reeve, fig. 6 b, Marquesas 



Islands; Sow. fig. 9. 



b. Forma obtusangula : A. Argo of most authors. Lister, Hist. Conch. 



pi. 555. fig. 7; Martini, Conchylien-Cabinet, vol. i. pi. 1/. fig. 157; 

 D'Orbigny, Cephalopodes, pi. 2. figs. 1, 2 ; Reeve, fig. 2% from 

 Venezuela ; Sow. Thes. fig. 2. 



c. Forma aurita : obtained at Ceram, Moluccas, by myself; Rumph, 



Amb. Rariteitkamer, pi. 18. fig. a, from Amboyna; Gualtieri, 

 pi. 12. fig. A ; Argenville, Concliyliologie, pi. 5. fig. a ; D'Orb. 

 Ceph. 2, 3-5. A. haustrum, Dillwyn; Reeve, fig. 2, from Tahiti; 

 Sow. Thes. fig. 1. 



Type of Argonauta tuberculata : — 



a. Forma mutica : one specimen from the coast of Brazil, in the Ber- 



lin Museum; Reeve, fig. 1. 



b. Forma obtusangula : some specimens in the Berlin Zoological Mu- 



seum. 



c. Forma aurita : Gualtieri, pi. 12. fig. b ; Argenville, 5 c ; Martini, 



figs. 156 & 160; D'Orb. Ceph. pi. 4 ; Reeve, fig. 2; Sow. fig. 3. 

 A. navicula, Solander. A. gondola, Dillwyn, on the authority of 

 D'Orbigny. 



