go JURASSIC RHYNCHONELLIDS 
Arkell (1956) thought the Neuvizy Ironstone to be of cordatum age, thus making it 
the lateral equivalent of the Terrain a Chailles which is cordatum and lower trans- 
versartum zones in age. This would then restrict avduennensis, as it was presumably 
conceived by Oppel, to those zones. 
Oppel proposed a new name for Orbigny’s R. inconstans as he realized that the 
Oxfordian species mentioned by Orbigny was not the one which had already been 
described by Sowerby (1821) under the name inconstans from the English Kimmer- 
idgian. As Oppel was proposing arduennensis as a new name for R. inconstans of 
Orbigny, it seems reasonable to assume that the species to which he was referring 
exhibited some degree of asymmetry. Therefore, it seems fairly certain that by 
avduennensis he meant the medium sized asymmetrical rhynchonellid occurring quite 
frequently in the Lower Oxfordian of the areas mentioned by him. As can be seen 
from the figured specimens, the species shows varying degrees of asymmetry but is 
occasionally perfectly symmetrical. The latter condition is shown by the specimen 
figured by Leidhold and this again has lead to some confusion. The species does not 
appear to have been figured other than by Leidhold and as Terebratula inconstans 
(pars) by Quenstedt. 
In making avduennensis the type species of his new genus septaliphoria, Leidhold 
gave no description and merely commented that it came from the “ Oxford-Stufe ”’ 
The caption to the one specimen figured described it as coming from the “ Oxford- 
Stufe ”’ of Méziéres. 
Rollier (1917) suggested the possibility of R. avduennensis Oppel bene a synonym 
of Terebratulites helveticus of Schlotheim (1813). The latter species was figured by 
Schlotheim but not given any description other than being listed as occurring in the 
“ Jurakalkstein ’’ near Basel and being given the citation “‘ Scheuchzer (1718), fig. 
105’. The latter figure is virtually indeterminable except as a ribbed brachiopod. 
Although Rollier maintained that R. helvetica “ est incontestablement une forme 
asymmetrique de ]’Oxfordian supér. et du Rauracien inférieur, trés, fréquente dans 
le Jura aux environs de Basle,” this statement seems to be erring on the side of 
optimism in view of inadequacy of the figures and the lack of detail given by both 
Scheuchzer and Schlotheim. Quenstedt (1871) considered the Schlotheim species 
to be his Terebratula lacunosa multiplicata from the “‘ Malm gamma ”’; this does not 
appear likely but at least demonstrates the uncertain nature of the species. It there- 
fore seems best to treat T. helveticus Schlotheim as a nomen dubium. 
The Tevebratula helvetica Schlotheim figured by Zieten (1831) possibly belongs to 
the genus Septaliphoria, but it is not considered to be conspecific with S. arduen- 
nensis. 
Septaliphoria paucicosta sp. n. 
(Pl. 9, figs. 5-6, text-fig. 33) 
1878 Rhynchonella lacunosa (Schlotheim); Davidson: 196-97, pl. 16, figs. 13-14. 
1917. Ehynchonella helvetica (Schlotheim); Rollier: 171. 
Name. Latin paucus-a-um, few ; costa-ae, rib: the species has relatively few 
ribs. 
