408 INFERIOR OOLITE AMMONITES. 



Sonninia paucinodata, 8. Buckman. See Plate XCI, figs. 7 — 9, and page 370. 



Sonninia attrita, 8. Buckman. See Plate XC, figs. 4—6, and page 371. 



The last four species, with the exception of Sonn. marginata, formed the 

 pauci?iodata-stock (p. 368). The L of the last is somewhat different from the 

 others, but not much. This may be due to phyletic septal degeneration. 



B. The lobes are fairly long. 

 A. The lobes are rather wide-stemmed. 



Fig. 39. — Outline of L of Sonn. dominata. 



Sonninia dominata, 8. Buckman. Plate XCVII, figs. 1 — 3. 



1892. Sonninia dominans (var. /3). This Monograph, p. 323, pars. 



Discoidal, compressed, carinate. Whorls ornamented with somewhat distant, 

 not prominent, somewhat irregular-sized, direct, slightly reclining, ventrally- 

 inclined costse, some of which are occasionally connate on the inner third, and 

 others obscure. (The regular spinous stage lasts to about 40 mm. diameter, the 

 irregular spinous stage, with rather numerous spines, another half-whorl.) 

 Ventral area obtusely arched, divided by a small, defined hollo w-carina. Inner 

 margin well defined, broad, slightly undercut, very slightly subconvex. Inclusion 

 about three-tenths. Umbilicus open, concentric, regularly graduate. Whorl- 

 section oblong-quadrate. Suture-line with short lobes; L asymmetrical, the 

 lateral lobules anisometric, inner lobule short and narrow, outer rather broad, 

 slightly bipartite, terminal lobule intra-axial, anisosceloid. 



From Sonninia dominans this species is separable by being more spinous, 



