MODERN CLASSIFICATION. 



245 



side with a projecting linguiforra process and two lateral grooves which extend to the 

 opposite side of the shell. Septa symmetrical, divided into four or six lobes each formed 

 of a pair of digitations. The ventral lobe equals in length the adjoining principal lateral, 

 which is longer than the lower lateral, and the columellar is small or absent. 



Genus Phylloceras, Suess. — Shell discoidal, highly involute, covered with very fine 

 striae which describe graceful forward bent lines (fig. 147). Body-chamber short, month- 

 border simple, with lateral lappets directed forward. Lobes numerous and very com- 

 plicated, as many as eight or nine on each side. Saddles bladder-shaped and well rounded 

 (fig. 148) ; body-chamber widely expanded and fan-shaped, wdth undulating radiations in 

 Phylloceras lieterophyllum. Sow. 



Fig. 146. — Disposition of the lobes Fig. 147. — Phylloceras heterophyllum, 

 (d, l, l', a) in Phylloceras hetero- Sow. Side view showing the lines 



phyllum. of growth. 



Fig. 148. — Disposition of the lobes 

 and saddles (d, l, if, a) in Phyll. 

 heferophyllum, Sow. 



Professor Neumayr' distinguishes, from the Dogger and Malm, four groups in this 

 genus, of which the following are types : — I. P/iyll. heteropliyllum. Sow. ; II. Phyll. 

 tatricum, Pusch ; III. Phyll. Capitanei, CatuUo ; IV. Phyll. ultramontanum, Zitt. 



This genus commences in the Trias with Phyll. debile, Hauer; Phyll Neojurense, 

 Quenst. ; Phyll. despectum, Mojs. ; Phyll. occultum, Mojs. In the Middle Lias Phyll. 

 Loscombi, Sow., Phyll. Zetes, d'Orb. In the Upper Lias Phyll. heterophyllum. Sow., 

 Phyll. subcarinatum. Young. In the Oxfordian Phyll. tatricum, Pusch., Phyll. viator, 

 d'Orb., Phyll. Hommairei, d'Orb., Phyll. Zignoanum, d'Orb. In the Cretaceous rocks 

 Phyll. subalpinum, d'Orb., Phyll. Velledee, d'Orb. Dr. W. Waagen has figured and 

 described^ several interesting species, closely allied to European forms, collected from 

 the Upper Jurassic rocks of Kutch, Western India, by the Geological Survey of India. 



1 Neumayr, " Phylloceratten des Dogger und Malm," ' Jahrbuch der Geol. Reicbsanstalt,' 1871, 

 bd. xxi. 



2 ' Palaeontologia Indica,' pis. v, vi, vii, p. 25, 1875. 



