PLATE XCVI. 



Concavum-zone. 

 Figs. 1, 2. — Sonninia modesta, 8. Buckman. 



Fig. 1. — Side view of a young shell, showing the early age at which the costate 

 stage commences. Test present. Bradford Abbas. From my father's Collection. 

 (Page 422.) (See also Pis. LXVIII and XCV.) 



Fig. 2. — Part of the peripheral area. 



Figs. 3 — 5. — Sonninia regularis, 8. Buckman. 



Fig. 3. — Side view, showing spinous and costate stages. The central whorls 

 of the umbilicus are damaged. Nearly all the test is present. Natural size. 

 Bradford Abbas. My Collection. (Page 395.) 



Fig. 4. — Part of the front view, showing the whorl-section and the large carina. 

 The carina of the embraced whorl is not sufficiently elevated in the drawing. 



Fig. 5. — Portions of outlines of two septa, showing a nearly symmetrical L, 

 with an axial, isosceloid terminal lobule and isometric laterals. 



Fig. 6. — Sonninia marginata, 8. Buckman. 



Fig. 6. — Portions of outlines of two septa from the type-specimen depicted in 

 PI. LXII, showing a somewhat asymmetrical L with anisosceloid, intra-axial 

 terminal lobule. (Page 407.) 



Fig. 7. — Sonninia ptycta, 8. Buckman. 



Fig. 7. — Parts of two suture-lines from the type-specimen illustrated in 

 PI. LXXIII, fig. 1, showing the very unequal size of the inner and outer lobules 

 of L, and the very intra-axial, anisosceloid terminal lobule. (Page 420.) 



(The suture-lines [figs. 5 — 7] are those of morphic equivalents, showing 

 the different development of the features of L. In fig. 5, L is symmetrical, isos- 

 celoid; in fig. G, somewhat asymmetrical, anisosceloid, but the lateral lobules 

 fairly isometric ; in fig. 7, very asymmetrical, anisosceloid, with abbreviated inner 

 lobule.) 



