MODERN CLASSIFICATION. 
255 
growth. Body-oliamber from two thirds to an entire whorl. Lobes similar to those in 
Stephanoceras, differing, however, in being more ramified, and having pendant columellar 
lobes. Aptychis bivalved, calcareous, very thin, and externally granular. PerispJnnctes 
Martinsii, d'Orb. (fig. 168), from the Inferior Oolite of France and England, is geologically 
the oldest of this group, which is largely developed in the Middle and Upper Jurassic 
strata of Europe ; a few species are found in the Chalk. 
The genus FerisjjJdnctes is represented in the Kachh Jura (Kutch)^ by more than 
fifty species, which can be distributed, according to Dr. W. Waagen, into six large 
sections, most of which comprise several groups embedded in strata which find their 
equivalents in the Middle and Upper Jurassic rocks of Europe among the Kelloway, 
Oxford, Corallian, Kimmeridgian, and Portlandian stages. 
Gems Olcostephanus, Nemn. — This genus was erected to receive a certain number 
of species that were formerly grouped with the preceding, but which are now separated 
from Perisphinctes. The type of this group is Olcos. Cautleyii, 0pp., from the Indian 
Jura. Olcostephanus, in contrast with PejispMnctes, has a shorter body-chamber, two 
thirds of a whorl in length. Mouth-border in some has a simple smooth band, and in 
others lateral auricles are developed. The ribs project broadly from the border of the 
umbilicus, and separate on the sides into many smaller branches. 
Gems ScAPHiTES, Park. — Shell spiral, rolled on the same plane. Whorls at first 
contiguous and united, then separated from the others and projected outwards in nearly 
Fig. 169. — Scaphites Ivanii, Puzos. 
a straight line, afterwards turned upwards, bent round, and curved inwards, forming a 
kind of horse-shoe shape. The septa transverse, symmetrically and regularly divided into 
more than six very unequal-sized lobes, invariably composed of short bilateral ramifications ; 
the saddles formed of bladder-hke cells. The siphonal lobe is as long as the principal 
lateral. The form of the inner whorls of ScapJiites corresponds with those of OJcosteplianns. 
Mouth-border round or oval, provided with large protuberant bands more or less 
prominent. All the species are found in the Cretaceous rocks. ScapJiites gigas, Sow. 
1 ' Palaeontologia Indica " Jurassic Fauna of Kiitcb," p. 143, 1875. 
