132 



MOLLUSC A. 



Nautilidse. 



This family includes those chanibered-shells having simple concave 

 septa, smooth sutures and an internal, simple siphuncle. With the ex- 

 ception of Nautilus and Aturia, it is confined to the Palaeozoic rocks 



The first true Nautilus with regular spiral appeared in the Upper 

 Silurian ; and the nautiloid form has survived to the present day. The 

 family culminated in the Carboniferous Age. The Nazttilits Pompilius 

 is one of the few representatives in the existing seas of that vast 

 assemblage of chambered siphoniferous shells which swarmed in the 

 Secondary and Palaeozoic oceans. 



No. 569. Nautilus bidorsatus, Sckloth. 



This species is marked by a broad shallow furrow following tke course of tke 

 outer whorls, thus giving the shell a double back or keel. From the Muschelkalk 

 (Trias), of Brunswick, Germany, and now in tke private Geological Cabinet of 

 Mr. Ward, Rochester. Size, 7x5. Price, $1.25. 



No. 570. Nautilus elegans, Sow. 



This very characteristic species of the Lower 

 Ckalk is from Havre, France, and now in tke private 

 Geological Cabinet of Mr. Ward, Rockester. 



Size, 10 s 9. Price, $2.25. 



No. 571. Nautilus intermedins, Sow. 



On pedestal. Tkis huge form, with a deep umbilicus and capacious mouth, 

 is from the Middle Lias, Ckarnioutk, England, and now in tke Ward Museum in 

 tke University of Rockester. Size, 12 x 9. Price, $2.75. 



No. 572. Nautilus latidorsatus, D'Orb. 



From the tipper Lias, Caen, Calvados, France, and now in the private Geo- 

 logical Cabinet of Mr. Ward, Rochester. Size, 10 x 8. Price, $1.25. 



No. 573. Nautilus Neocomiensis, D'Orb. 



This specimen shows the shell with the sinuated markings tkat very gener- 

 ally ckaracterize cretaceous species of tkis genus. From tkeNeocomian (Lower 

 Cretaceous), Escragnolles, France, and now in tke private Geological Cabinet of 

 Mr. Ward, Rockester. Vrxce, $1.00. 



No. 574. Nautilus pseudoelegans, D'Orb. 



This is closely allied to the preceding. It is 

 an inner cast, and shows the septa of the shell. 

 From the Chalk of Rouen, France, and now in 

 tke Ward Museum, University of Rockester. 



Size, 6x5. Price, $1.00. 



