213 
S = S 
Ni 
Fia. 73.—Hoplites faleatus, Mantell. Fic. 74.—A. Beawmontianus, d’Orb. 
lateral ribs may be folded and angular, as in Hopl. falcatus, 
Manr., fig. 73, or large and powerful, as in Hopl. interruptus, 
Bric. There is a considerable variety in the style of the rib 
sculpture and the form it assumes in this genus. The mouth- 
border and the length of the body-chamber are at present 
unknown. 
The suture-line is much ramified in Hoplites interruptus, Bric. 
The siphonal lobe and two principal laterals are about the 
same length, with numerous branches, having a symmetrical 
arrangement; the second lateral is much smaller, and there are 
several auxiliaries. In general the lobe bodies are slender, the 
saddles broader than the lobes, the principal lateral is often 
longer than the siphonal, the second lateral very short, and 
there are several horizontal or oblique auxiliaries. 
This genus is very characteristic of the Cretaceous period, 
and its highly ornamented shells form conspicuous groups in 
the different stages of the Chalk age. 
Genus AcantHoceras, Newm.—This new group has been 
proposed to receive several remarkable Ammonites which were 
included in the genus Hoplites, a more extended study of 
them having induced Prof. Neumayr to separate them into a 
distinct genus, of which the following is a diagnosis :—‘ The 
shell is wider and more massive; the umbilicus more open; 
the whorls moderately high; mouth-border and body-chamber 
both unknown.” The sculpture consists of strong straight ribs, 
which proceed from the suture-line along the sides, or strong 
