MODERN CLASSIFICATION. 
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shorter than the principal lateral lobe, which is mostly broad and wedge-shaped. A 
divided horny Anaptychus has been found in this genus. 
The genus Amaltheus has an extensive geological range ; it is found in the Trias, 
Amal. meyalodiscus, Beyr., Ainal. Jloridus, Wulf. ; it is largely developed in the Jurassic 
strata^ commencing with Amal. Guibalianus, A' Oxh., Amal. maryaritatiis, lA.ont. (fig. 134), 
and Amal. spinatus, Brug., in the Lias, and many forms are found in the higher Oolitic beds, 
as Amal. cordatiis, Sow., Coral Rag (fig. 135) ; numerous species are likewise discovered 
in the Cretaceous rocks, as Amal. Gevrilianus, d'Orb., Amal. Vibrayeanus, d'Orb. 
Genus Schloenbachia, Neim. — Shell keeled, with strong forward-bent ribs on the 
sides, sometimes developing lateral tubercles. Body-chamber two thirds of a whorl 
long. Mouth-border falciform, ventral side with a forward directed process. Siphon 
Fig. 136. — Schloenbachia Roissyana, Fig. 137. — Schloenbachia Fig. 138. — Schloenbachia Goupilanus, 
d'Orb. cristata, Deluc. d'Orb. 
large, mostly lodged in the high keel (fig. 137) ; this genus is entirely limited to the 
Cretaceous rocks; figs. 136, 137, and 138 represent typical forms of the group. 
II. Family. — TaopiTiDiE, Mojs. 
Shell more or less richly ornamented, and provided with radial ribs, which almost 
always support tubercles or spiny processes on the border of the siphonal area. Wrinkle- 
layer and impression on the surface of the mantle entirely wanting. 
Genus Tropitbs, v. Mojs. — Body-chamber from one and a half to one and three 
quarters of a whorl in length. The strong-ribbed sculpture is interrupted upon the 
ventral surface, and rises as a median keel on the same. The ventral side of the mouth- 
border projects forward in a short broad lappet ; the last whorl seldom loses the form 
and sculpture of the inner whorls. The lobes are characterised by a broad saddle stem 
with transverse incised branches, a transverse placing of the lobe points, great develop- 
ment of the chief lobes, and a remarkable diminution of the auxiliaries. All the species 
are Triassic. Ex. Tropites Pamphayus, Dittm., Trop. 8aturnus, Dittm. 
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