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 of 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 of A. Argo: ribs smooth and numerous; keel nar- 
row; colour white. : 
2. Type of A. tuberculata, Shaw (nodosa, Solander, tubercu- 
losa, 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 4. Argo and tuberculata, and in many of A. hians. 
Within each of these types there are specimens in which the 
lateral edge of the aperture 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. 64, Marquesas 
Islands; Sow. fig. 9. 
b. Forma obtusangula: A. Argo of most authors. Lister, Hist. Conch. 
pl. 555. fig. 7; Martini, Conchylien-Cabinet, vol. i. pl. 17. fig. 157; 
D’Orbigny, Céphalopodes, pl. 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, pl. 18. fig. A, from Amboyna; Gualtieri, 
pl. 12. fig. a; Argenville, Conchyliologie, pl. 5. fig. a; D’Orb. 
Céph. 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, pl. 12. fig. B ; Argenville, 5c; Martini, 
figs. 156 & 160; D’Orb. Céph. pl. 4; Reeve, fig. 2; Sow. fig. 3. 
A. navicula, Solander. A, gonda Dillwyn, on the authority of 
D’Orbigny. 
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