256 



THE LTAS AMMONITES. 



(fig. 170). I have collected magnificent examples of this grand form, occuring in 

 nodules, from eighteen inches to two feet long, in the Lower Greensand at Whales Chine, 



Fig. 170. — Scaphites gigas, Sowerby. 



near Black-Gang, Isle of Wight. Scaphites Ivanii, Puzos (fig. 169), is from the Lower 

 Neocomian ; and Scaphites nequalis, Sow., is found in the Lower Chalk at Lewes, Sussex, 

 and Chardstock, Somerset. 



Genus Hoplites, Neum. — This genus is composed of a series of species formerly 

 classed among Perisphinctes, but now separated as a new genus, characterised by 

 having the shell closely involute, with high whorls andja narrow umbilicus. Sculpture 

 consists of numerous small undulating ribs, often polytomate (fig. 171), that is, arising, 

 by a thickened stem or tubercle, from near the umbilical suture, and soon splitting up into 

 smaller divisions ; sometimes the ribs encircle the siphonal area, or are interrupted here 

 either by their vanishing away at the border of the area, or by a median channel, which 

 breaks their continuity, or by a kind of crest formed by the abrupt termination 



Fig. in. 

 Hoplites falcatm, Mantell. 



Fig. 172. 

 Hoplites Beaumoniianits, d'Orb. 



of the lateral ribs, as in Hopl. splendens, Sow. ; or the lateral ribs may be folded and 

 angular, as in Ho'pl.falcatus, Mant., or large and powerful, as in Hopl. interruptus, 

 Brug. There is a considerable variety in the style of the rib-sculpture and the form it 



