372 INFERIOR OOLITE AMMONITES. 
Sonn. attrita is the form alluded to at page 340 as not unlike parvicostata, but 
as probably belonging to a different stock. Since then, some portion of the test 
has been successfully removed ; and it is now possible to say to what stock it does 
belong, on the evidence of its suture-line. It may be remarked that the want of 
symmetry in the superior lateral lobe prevents this form being included in the 
costata-stock ; while external differences from S. parvicostata are the spinous 
centre and the smaller umbilicus—these features alone point to a difference in 
ancestry. 
Sonn. attrita occurs in the Concavum-zone of Bradford Abbas. In PI]. XC, 
fig. 4 shows the side view, one-half reduced, of a partially-shelled specimen with 
half a whorl of body-chamber ; fig. 5, the outline of the front view similarly 
reduced; fig. 6, the suture-line with its asymmetrical superior lateral lobe, of 
natural size. 
Species of different Stocks. 
The following species, from the combination of characters they possess, 
appear to be somewhat isolated,—at any rate, they cannot be placed in any of 
the preceding stocks. They are very different from each other, and the only 
bond between them is their respective isolation, from not possessing any close 
allies. Such forms will no doubt appear in time; for it is noticeable that since 
the following articles were first penned several species have been removed from 
this association: by continued work allied forms have been discovered, and the 
species could no longer be treated as incertx sedis. For several reasons the 
description of such species is conveniently postponed until their allies are figured. 
Sonninia patmata, S. Buckman. Plate XC, figs. 7—9. 
Discoidal, compressed, hollow-carinate. Whorls ornamented with direct, 
reclining, ventrally-inclined, undulate, not very conspicuous cost, which become 
considerably more distant on the last whorl. (The irregular spinous stage ends 
at about 60 mm. diameter.) Ventral area arched, divided by a small, distinct 
hollow carina. Inner margin narrow, rising steeply, but upper edge much 
rounded off. Inclusion about one-third. Umbilicus with slightly gibbous whorls, 
of which the earlier are ornamented with spines and ribs. Section of last whorl 
elliptical. Suture-line with a bifid superior lateral lobe—the outer portion 
