SONNINIA ABNORMIS. 377 



Ventral area rather flattened, rounded, divided by a small, rounded, fairly-defined, 

 presumably hollow carina. Inner margin fairly defined, steep, convex. Inclusion 

 about one-third. Umbilicus rather flat and open. Whorl-section oblong. Suture- 

 line simple, the superior lateral lobe symmetrical, the lateral lobules much abbrevi- 

 ated, equipoised, bipartite, the terminal lobule axial, isosceloid, and equicellate. 1 



A peculiar character in this species is the intervention of a short costate stage 

 between two spinous stages — a feature not seen in any of the species hitherto 

 described ; but it is noticeable in some to be mentioned later. The same 

 character, for instance, may be seen in Sonn. reformata (PL LXXXIX, figs. 6 — 8) ; 

 but in that case it is associated with a complex suture-line (fig. 8). In the 

 present species the suture-line is very simple, therefore it is hardly possible that 

 there can be any close genetic affinity between these two forms. 



The following species may be considered as more or less morphically equivalent 

 to Sonn. scalpta : 



Sonn. subcostata (PL LXXI, fig. 4), which has a smaller umbilicus, greater 

 thickness, and connate sub-costas. 



Sonn. omphalica (PL LXXXIII, figs. 5 — 7) shows whorls (the outer one 

 especially) more costate, a less spinous centre, and different whorl- section. 



Sonn. eur omphalica (PL LXXXV, figs. 1 — 3), more spinous centre, coarser 

 costee, less compressed whorls. 



This cryptogenetic, and therefore most interesting form, Sonn. scalpta, is 

 represented only by the one specimen depicted, of natural size, in PL LXXXVII 

 — side and front views, figs. 1,2; and suture-line, fig. 3. It is a beautiful example, 

 showing all details of the test with the greatest clearness, both sides being almost 

 equally well preserved. It owes its discovery to Mr. Darell Stephens, F.G.S., to 

 whose collection it belonged. It came from the Concavum-zone of Bradford Abbas. 



Sonninia ABNORMis, S. Buchnan. Plate LXXXV, figs. 4 — 6. 



Discoidal, compressed, hollow-carinate. Whorls ornamented at first with 

 fairly large, regular spines, later with costse and spinicostas as about 1 to 2 ; 

 then the spinicostse decline to swollen ribs, separated by smaller ribs at inter- 

 vals, about 2 to 1 ; nearly all the ribs slightly reflexed, reclining, very little 

 ventrally-inclinecl, and bifurcate on the outer area. Ventral area not defined, 

 rounded, divided by a small, well-defined hollow carina. Inner margin ill-defined, 

 slightly indented for spines, convex, steep. Inclusion about one-third. Umbilicus 



1 The upper superior lateral lobe in fig. 3 (PI. LXXXVII) is, owing to indifferent preservation, 

 not quite so trustworthy as the lower one. 



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