FROM NORTHWESTERN EUROPE 55 
OccURRENCE. The genus has been collected by the author only from coarse, 
bioclastic limestone. 
REMARKS. On account of their distinctive appearance members of Acanthothiris 
have been described and figured on numerous occasions, usually under the name of 
Rhynchonella, Terebratula or Acanthothiris spinosa. The author has not attempted 
to disentangle the nomenclature and synonymy of these numerous descriptions and 
figures, but has here only attempted to define and clarify the type species together 
with A. cf. costata, which happened to be a very common fossil in the part of the 
southern French Jura mapped by members of Imperial College. The latter species 
was investigated in order to obtain a wider knowledge of the variation of internal 
structures of the genus as these are not adequately described in the literature. 
Acanthothiris spinosa (Linnaeus) 
(Pl. 5, figs. 12-17, text-figs. 21-22) 
1767 Anomia spinosa Linnaeus: 1154. 
1768 (concha) anomia ventricosa, striata echinata, d’Annone in Knorr and Walch: go, pl. B4, 
fig. 4. 
1779 Anomia Walcott: 21, fig. 31. 
1813 Tevebratulites spinosus Schlotheim: 73. 
1813 Anomia spinosa Linnaeus; Townshend: 372. 
1817 Tevebratula spinosa Smith: 108. 
1820 Tevebratulites spinosus Schlotheim: 269. 
1825 ?Levebratula aspera Koenig: fig. 219. 
1829 Tevebvatula spinosa Townshend and Smith; Phillips: 123, pl. 9, fig. 18. 
1833 Tevebratula spinosa Buch: 58-59. 
1838 Tevebvatula spinosa Buch: 161-62, pl. 6, fig. 4. 
1850 Hemithiris spinosa Orbigny: 268. 
1850 Acanthothiris spinosa Orbigny: 323. 
1851 Rhynchonella spinosa (Schlotheim); Davidson: 71-73, pl. 15, figs. 15-20. 
1857 Rhynchonella spinosa (Schlotheim); Deslongchamps: 355-56, pl. 5, fig. I. 
1858 Rhynchonella spinosa (Schlotheim); Davidson: 222. 
1882 Rhynchonella spinosa (Schlotheim); Buckman: 40-41. 
1889 Acanthothyris spinosa (Linnaeus); Buckman and Walker: 12-14. 
1900 Acanthothyris spinosa (Schlotheim); Greppin: 178-80, pl. 19, fig. 3. 
1917 Acanthothyris spinosa (Schlotheim); Rollier: 76-77. 
1918 Acanthothiris spinosa (Linnaeus); Buckman: 70-72, pl. 19, fig. 26. 
1936 Acanthothiris spinosa (Linnaeus); Muir-Wood: 28. 
1936 Acanthothyris spinosa (Schlotheim); Arcelin and Roché: 54-58, pl. 1, figs. 1-18, pl. 12, 
fig. 2. 
1959 Acanthothyris spinosa (Schlotheim); Henry: 119-21. 
1966 Acanthothiris spinosa (Schlotheim); Alméras: 277-79, pl. 17, figs. 1-3. 
EMENDED DIAGNOsIS. Medium to large sized Acanthothiris ; relatively globose ; 
outline subpentagonal ; brachial valve considerably more inflated than the pedicle ; 
“ pedicle trough’ present ; well marked uniplication ; 30-35 ribs on each valve ; 
crura radulifer. 
TYPE SPECIMEN. Neotype, here proposed, is the specimen in the collection of the 
B.M.(N.H.) from the Inferior Oolite of Rodborough Hill numbered B4030. The 
