394 THE LIAS AMMONITES. 



The extreme involution of the shell and the size and height of the outer whorl are 

 the distinguishing features of this Ammonite. The sides are regularly convex, and orna- 

 mented with numerous slightly-elevated folds, best seen on the surface of the mould; in 

 the lower two thirds they have a gentle inclination forward, in the upper third they bend 

 more towards the aperture, a style of curvature which appears to be common to the entire 

 group of the Oxynoti. The shell is only partially preserved. It is thin on the sides and 

 thicker near the umbilicus ; the surface appears to have had fine lines on the surface, 

 which followed the bend of the folds. Both my specimens have suffered in cleaning, 

 and the delicate shell sculpture is indistinguishable. The keel is blunt, from a thickening 

 of the shell around this region, and I have failed to observe the position of the siphuncle. 

 The aperture is extremely lanceolate, and deeply encroached upon by the turn of the 

 spire and the penultimate whorl. 



The lobe-line is a very elegant and complicated foliation (fig. 3). The siphonal lobe 

 has two long terminal diverging branches on each side, and several lateral ones with many 

 digitations. The siphonal saddle is very complicated, and divided into two portions by 

 a long central branch ; the folioles are numerous, narrow, and deep. The principal 

 lateral lobe is a large complicated structure, it has two large lateral branches internally, 

 and three small digitations externally, and two branched terminal twigs. The lateral 

 saddle is nearly as large as the principal lobe, and ends in four or five long, narrow- 

 branched folioles. The lateral lobe is much smaller than the principal lateral, and iias 

 two lateral branches on each side, and a terminal one with three divisions. The lateral 

 saddle is smaller but more regularly formed than the principal saddle, and terminates 

 in many foliations. The auxiliary lobes, four or five in number, are elegantly branched, 

 and the auxiliary saddles diminish in the size and number of their parts as they approach 

 the umbihcus, the great height of the whorl necessitates a greater number and extension 

 of the auxihary lobes and saddles. 



Affinities and Differences. — This Ammonite very much resembles Amah Lymensis. It 

 is altogether a more rotund shell, with more convex sides, and has a different style of 

 lobe-line, which is apparent when we compare PI. XLVII, fig. 3, withPl. XLVIII, fig. 3. 



Locality and Strati yraplncal Position. — This Ammonite was obtained from the Green 

 Ammonite Bed, near Charmouth, containing Belemnites lonyissimus. Miller, and Belem- 

 nifes elonyatus. Miller, and others that are indeterminable. I have found no other shells 

 associated with it. 



