7o JURASSIC RHYNCHONELLIDS 
and the other “‘ Oxfordien”’ in age. To remedy this he proposed that the name 
spinulosa be restricted to the larger, oval species from the “ Argovien ”’ and that the 
smaller, pyriform species of the ‘‘ Oxfordien moyen et supérieur ’”’ be designated 
Acanthothyris lorioli sp. nov. Rollier’s reason for preferring to restrict the name 
spinulosa to the larger form was that he considered Oppel’s original designation 
inadequate and that, of the two species in question, this seemed to him to be the 
more likely to have been known to Orbigny, judging from the localities cited in the 
“ Prodrome ” 
Plaster casts of the specimens labelled Hemithiris senticosa in the Orbigny collec- 
tion at the Jardin des Plantes, Paris, were kindly made available to the author by 
the curator, Dr. Fischer. These specimens are in two boxes labelled 3782, contain- 
ing three specimens from Chatel Censoir (Yonne) and 3782a, containing two speci- 
mens from Nantua (Ain). Both of the collection numbers contain a specimen of 
both A. (Echinirhynchia) lorioli and A. (Acanthorhynchia) spinulosa sensu Rollier. 
None of the specimens is referable to A. senticosa (Schlotheim). One of the speci- 
mens labelled 3782 probably belongs to a third, undescribed species and closely 
resembles a form collected by Dr. Evamy from the southern French Jura of Ain. 
Unfortunately not enough specimens of this form have been collected to make a full 
taxonomic investigation possible. 
From the investigation of the original Orbigny material, described above, it seems 
that neither Oppel nor Rollier realised the diversity of specimens included by 
Orbigny under the name Hemithiris senticosa. However, the author would agree 
with Rollier’s conclusions and these are here followed. 
A. (Acanthorhynchia) vilsensis sp. n. 
(Pl. 6, figs. 10-12, text-fig. 26 (bottom)) 
1886 Rhynchonella myriacantha Deslongchamps; Rothpletz: 156, pl. 12, figs. 24-27. 
NAME. From the type area of the “ Vilser Alp ”’ in the Tirol. 
Diacnosis. Medium sized Acanthorhynchia with rather coarse ribbing ; beak 
suberect ; uniplication in anterior commissure. 
STRATIGRAPHICAL RANGE. Given by Rothpletz as Callovian—macrocephalus to 
lambert zones. 
TYPE SPECIMEN. The holotype designated is the specimen figured by Rothpletz 
(1886) pl. 12, fig. 25, which came from Legam bei Vils in the Tirol ; this specimen is 
now in the Bayerische Staatsammulung ftir Palaontologie und historische Geologie 
in Munich, and is numbered AS xiv 2. 
MATERIAL. 17 specimens from the Bayerische Staatsammulung. 
DESCRIPTION. External characters. The adult specimens are biconvex, trans- 
versely oval in outline and with the width always greater than the length, while the 
juvenile forms have a subcircular outline. The beak is suberect ; beak ridges and 
interarea are only very weakly developed. In nearly all the specimens examined, 
the beak had been broken off about level with the top of the brachial valve. Ina 
few more complete specimens, the delthyrium appears to be open but this feature 
