FROM NORTHWESTERN EUROPE 97 
Remarks. The genus Torquirhynchia has been proposed in order to group to- 
gether the various distinctively asymmetrical rhynchonellid species of the Upper 
Jurassic. Many of the included species have previously been attributed to Rhyncho- 
nella astiertana Orbigny. 
The Upper Jurassic, asymmetrical rhynchonellids have also been frequently 
referred to the genus Septaliphoria Leidhold, largely as a result of the paucity of 
generic names at this stratigraphical level and the lack of information regarding the 
diagnostic characters of the type species of that genus, namely S. arduennensis 
(Oppel). Internally, Torquirhynchia is readily distinguished from Septaliphoria by 
its weakly developed septalial plates and the position and development of the crural 
bases relative to them. Externally, the adult specimens of Torquirhyncmia attain a 
much greater size and are always strongly asymmetrical whereas specimens of 
Septaliphoria are only weakly asymmetrical or are symmetrical. 
Torquirhynchia inconstans (J. Sowerby) 
(Pl. 10, figs. 1-3, pl. 12, fig. 5, text-fig. 34) 
1821 Terebratula inconstans J. Sowerby: 137, pl. 278, fig. 4. 
1834 Tevebratula inconstans J. Sowerby; Buch: 45-46. 
1838 Tevebratula inconstans J. Sowerby; Buch: 146, pl. 14, fig. 16. 
1852 Rhynchonella inconstans (J. Sowerby); Davidson: 87-88, pl. 18, figs. 1-3. 
1878 Rhynchonella inconstans (J. Sowerby); Davidson: 191-93, pl. 16, figs. 1-6. 
1917 hynchonella inconstans (J. de C. Sowerby) (sic); Rollier: 177-78. 
1918 Rhactorhynchia inconstans (J. Sowerby); Buckman: 51. 
EMENDED DIAGNOSIS. Medium sized, globose Torquirhynchia ; strongly devel- 
oped beak ridges and interarea ; 25-30 simple angular ribs ; crura radulifer. 
STRATIGRAPHICAL RANGE. Kimmeridgian—baylei to cymodoce zones. 
TYPE SPECIMEN. Lectotype, here selected, fig. 4, pl. 277 of Sowerby (1821) ; 
the specimen is from the Kimmeridge Clay of Ringstead Bay, Dorset, in B.M.(N.H.) 
Sowerby Coll. No. B. 61475. 
MaTERIAL. More than 100 specimens from the collection of the B.M.(N.H.) 
mostly from the Dorset Coast but also including a limited number of specimens from 
inland localities. 10 specimens in the author’s collection obtained from Ringstead 
Bay. 
DESCRIPTION. External characters. The shell outline is subpentagonal and the 
valves are equally biconvex. The radial ornament consists of about 25-30 simple, 
angular or subangular ribs which show neither intercalation nor bifurcation, while 
the concentric ornament consists of numerous fine growth lines and occasional weak 
growth lamellae. In the flatter specimens the strongly developed beak is erect but 
the extent of the incurvature is obviously dependent on the globosity of the shell and 
in very globose specimens the beak is adpressed to the brachial valve. 
The relatively small hypothyridid or submesothyridid pedicle opening is flanked by 
small disjunct or conjunct deltidial plates. Beak ridges are clearly marked and 
bound the well developed interarea ; the latter may be flattened but is usually 
strongly incurved. 
