134 VON IHERING — MOLLUSC AN FAUNA OF PATAGONIA. [April a- 



Nautilus caroli-ameghinoi, sp. nov. 



(Plate XIX, Figs, i, 2.) 



Nautilus testa suborbiculari, imperforata, leevi, suturis simplicibus, 

 siphone interno, in fundo foss^ latae situ. 



The shell, which is filled with matrix and not very well preserved, 

 is of suborbicular shape, subcompressed and much enlarged toward 

 the aperture. The outer or peripheral part of the shell is rounded, 

 smooth and with simple sutures. There is no umbilicus, but a pit 

 at the central point of origin of the outer lip of the body-chamber. 

 In this groove, the wall of which covers the umbilicus, there is, 

 opposite to the origin of the outer lip, a crista, the prolongation of 

 which passes into the dorsal wall of the body-chamber. The siphon 

 is placed at the bottom of a large and deep hollow, which has an 

 internal situation — that is to say, nearer to the dorsal than to the 

 ventral or external margin of the septum. 



Measurements. 



Major diameter 74 mm. 



Minor « 58 " 



Body-chamber, length 42 *' 



*< « breadth, central 34 " 



" " « in the middle 29 '« 



I take great pleasure in dedicating this new species, which is the 

 first representative of the class Cephalopoda from the Tertiary of 

 Patagonia, to Mr. Carlos Ameghino, whose excellent work in the 

 geological exploration of Patagonia I appreciate very highly. 



Locality : Golfo de San Jorge, Cabo Tres Puntas. 



Formation : '^ Patagonico medio." 



Neoinoceramus ameghinoi, gen. et sp. nov. 



(Plate XIX, Figs. 3, 4.) 



Testa solida, compressa, oblique-ovata, antice posticeque paullulum 

 hiante, concentrice laminato-costata, laminis altis subreflexis 

 distantibus, interstitiis loevibus ; auriculis anticis magnis, 

 posticis minoribus ; area ligamentale lata brevi. 



The shell is large, solid, very obliquely ovate, slightly compressed 

 and gaping on both sides. The anterior lateral margin is convex, 

 passing gradually into the arched ventral margin ; the posterior 



