624 Appendix to Part II 



DESCRIPTIONS OF SECONDARY FOSSIL SHELLS 

 FROM SOUTH AMERICA. 



By Pbofessoe E. FORBES, F.R.S., &c, &c 



Nautilus l'Oebigxyanus. — PI. V. fig. 1. (a) 1. (b). 



Shell ventricose {probably smooth and slightly umbilicatedf). Mouth 

 very broad, reniform. Black rounded. Sutures bend, suddenly 

 towards, and near to, the umbilicus ; on the back they are very 

 slightly sinuated. 



This specimen is very imperfect. The form of the chambers 

 resembles that seen in Nautilus Soioerbyanus, a species described 

 from the upper greensand by D'Orbigny. The general form more 

 nearly resembles Nautilus Icevigatus of the same author, a species 

 also from the Crate chloritee. 



Concepcion, Chile. 



Halites elatiok. — G. B. Sowerby. 



Testa magna, crassiusculd, Icevi, subcylindricd, annulis elevatis, 

 conspicuis, subco7ife7'tis, ornatd ; extremitatibus invieem prope 

 admotis. 



This is the largest Hamite I have seen; it is nearly cylindrical, 

 and its largest diameter is 2| inches, its smaller being 2^. There 

 are two specimens, one of which is much larger than the other. 

 The smaller shows clearly the near approximation of the two 

 extremities. The specimens have been lost since Mr. Darwin's 

 return to England, and so cannot be figured. 



Port Famine, Tierra del Fuego. 



Peexa Americana. — PI. V. figs. 4, 5, 6. 



Shell lanceolate ? ventricose, carinated, compressed in the ca?'dinal 

 region, abruptly truncate, concave at the opposite side, so that the 

 section of the two valves is triangular and somewhat cordate, 

 The sukations of the hinge are large, numerous, and regular. 



