THE CEPHALOPODA. 



199 



iirst contiguous, then separated from the others and projected in nearly a straight line, 

 afterwards bent upwards and forwards, forming a horse-shoe curve. Septa transverse, 

 symmetrical, divided regularly into unequal lobes. The recurved portion always without 



Fig. 87. — Scaphites gigas, Sowerby. 



septa, formed the dwelling chamber of the animal. Siphuncle continuous and marginal. 

 Mouth oval, provided with large protuberent bands, more or less prominent. All the 

 species are obtained from the Cretaceous formation, and very large forms are obtained 

 from the Neocomian strata. Scaphites gigas, Sow. (fig. 87), and Scaphtes Ivanii, Puzos, 

 (fig. 88), are typical forms of this group. 



-Scaphites Ivanii, Puzos. 



Genus Ancyloceras, d'Orhigny. Shell spiral, rolled on the same plane, with very 

 few whorls perfect, and not contiguous ; the last separated from the others and projected 



Fig. 89. — Ancyloceras Matheronianum, d'Orb. 



outwards in a horizontal line, then turned upwards and inwards, forming an arch opposed 

 to the turns of the spine, the recurved portion without septa formed the dwelling chamber. 



