420 INFERIOR OOLITE AMMONITES. 



Sonninia pttota, 8. Buckmaii. Plate XCVT, fig. 7. 

 See Plate LXXIII, fig. 1, and page 332. 



Add to description : suture-line with L asymmetrical — the terminal lobule very 

 anisosceloid, intra-axial, and inequicellate ; the lateral lobules very anisometric, the 

 inner lobule being very much abbreviated. 



Compared with the suture-line of acanthodes the lobes are altogether shortened, 

 L has become more asymmetrical, and its inner lateral lobule is very considerably 

 abbreviated. The septal outlines of 8. ptycta have been placed on the same plate 

 with those of its morphic equivalents, Sonn. marginata and Sonn. regularis. The 

 differences between them are noticeable, and attention is drawn to them in the 

 explanation of the plate. 



Sonninia cymatera, 8. Buckman. Plate C, figs. 5 — 7. 

 See Plate LXXIII, figs. 2, 3, and page 332. 



In the description (page 332), for " somewhat reclining '' read " strongly reclin- 

 ing ;" the former is certainly an oversight. 



Add to description : suture-line with short lobes ; L with very intra-axial, ani- 

 sosceloid terminal lobule ; lateral lobules anisometric. 



Compared with the suture-line of ptycta (PL XCVI, fig. 7), there seems to be a 

 general shortening in the lobes of cymatera, and even a shortening in the outer 

 lobule of L. The lobes figured in PI. C, fig. 7, are those of an adult example, shown 

 of reduced size in fig. 5. The suture-line of the young type could not be made to 

 show with sufficient clearness for tracing, but enough detail was observed to 

 indicate its agreement with that of the specimen figured in PI. C. This specimen 

 agrees with it in ornament and proportion : it shows the persistence of strong 

 ribs in maturity, and their reclination seems to increase. 



C. The lobe remains long, but L becomes very asymmetrical, 

 a. Inner lobule of L much abbreviated in spinous species. 



Fig. 48. — Outline of L of Sonn. gibbera. Fig. 49. — Outline of L of Sonn. modest a. 



