198 
THE LIAS AMMONITES. 
foliated. The Ligati are all Cretaceous forms, and Haploceras ligaiiim, d'Orb. (fig. 84), 
from the Neocomian, is a typical species. 
18th Section. Planulati, von BucJi. See p. 189 
19tli Section. Coronarii, vo7i Buck. See p. 190. 
20th Section. Macrocephali, vo?i Buck. See p. 190. 
21st Section. Ym^mkii, d' Orbipiy. Shell discoidal ; formed of cylindrical whorls ; 
often contiguous and without involution ; smooth, or ornamented transversely at regular 
distances apart, with prominent ribs or grooves, which are the remains of a portion of 
the mouth appendages of the species. Mouth circular. Septa symmetrical, formed of 
lobes and saddles divided in part into pairs, always enlarged at their extremity and 
narrow at the base; siphonal lobe often the longest. Aecjoceras fimhriatum. Sow. (fig, 85), 
of the Middle Lias, is a good type of this group. The Fimbriati are found in the 
Jurassic rocks and Lower Cretaceous strata. 
Fig. 84. — Haploceras ligatum, d'Orb. Fig. 85. — Aetjoceras iimhriatum. Sow. Fig. 8G. — Crioceras Emerici, Leveille. 
Ji. Species with ramified septa ; tohorls coiled spirally on the same jjlane, not contiguous. 
Genus Crioceras, Leveille. Animal unknown. Shell discoidal, rolled on the same 
plane, whorls round or oval, and not contiguous. Septa transverse, divided regularly 
into six lobes, mostly formed of single parts, the siphonal lobe excepted, and the saddles 
formed of parts nearly always in pairs. The superior lateral lobe is longer than the 
siphonal lobe. The lobes and the saddles are narrow at the base and much enlarged at 
their extremity. Siphuncle continuous, always marginal. Two thirds of the last whorl 
formed the dwelling chamber of the animal. Pound in the lower strata of the Cretaceous 
formation. Crioceras Emerici (fig. 8G) is a typical form. 
Genus Scaphites, Parkinson. Shell spiral, rolled on the same plane; whorls at 
