58 JURASSIC RHYNCHONELLIDS 
the serial sections. The pedicle opening can be seen at the base of the pedicle 
groove ; the difference in appearance of this structure, as compared with A. cf. 
costata results from the greater incurvature of the beak in A. spinosa. 
Brachial valve. See generic description. The shape of the crura seems to be a 
useful criterion for differentiating the species from A. cf. costata. 
DISTRIBUTION. The species has been definitely recorded from the Cotswolds, 
Normandy, northern France, around Basel in Switzerland and from Monsard 
(Sadne et Loire). The name spinosa has been used frequently in the past for any 
spinose rhynchonellid and consequently from the literature, it is very difficult to 
ascertain the true distribution of A. spinosa s.s. 
OCCURRENCE. The species is considered to have lived under conditions similar to 
those described for A. cf. costata. 
REMARKS. The rhynchonellid now known as Acanthothiris spinosa s.s. was first 
figured by Knorr and Walch (1768) with the description, “‘ concha anomia, ventri- 
cosa, striata echinata’’, which was given by Professor d’Annone. A specimen 
regarded by Rollier (1917) as the type of Knorr and Walch is preserved in the 
Naturhistorisches Museum of Basel ; however, as Rollier pointed out, this specimen 
differs markedly from the original figure in such features as the number of ribs, of 
which the specimen has 36-38 on the pedicle valve rather than the 26 figured. This 
discrepancy is such that Dr. Gasche, of the Museum, is of the opinion (personal 
communication 1965), that this is not the original of the Knorr and Walch figure and 
the present author would concur with this observation. 
Linnaeus (1767)* described Anomia spinosa, stating that it had long spines and 
that it came from England. Although, unfortunately, the original is not preserved 
in the Linnaeus Collection, at present in the B.M.(N.H.), it seems reasonable to 
assume that the A. spinosa referred to by Linnaeus is the very common Inferior 
Oolite species of Acanthothiris. This was the view taken by Muir-Wood in her 1936 
monograph. Therefore, it has been decided to define the species with a neotype 
from the Bajocian of the Cotswolds. 
The confusion over the authorship of the species has arisen mainly as a result of 
Schlotheim (1813) mentioning a Terebratulites spinosus, which he did not figure or 
describe, but merely referred to the figure of Knorr and Walch. As this figure was 
not named in the correct binomial form and as it is regarded by the present author as 
conspecific with Anomia spinosa of Linnaeus, the Schlotheim name must be regarded 
as a synonym and the species attributed to Linnaeus. 
In 1889 Buckman and Walker fully discussed the earlier literature and redescribed 
all the known British spinose rhynchonellids. Rollier added to the confusion by 
setting up many new species based purely on published figures, many of which were 
wholly inadequate in the first place. Buckman (1918) redefined the genus and 
* This is the first edition in which spinosa is described and at the end of the remarks on habitat, which 
mention that the species occurs in England, is written ‘‘ Solander’’. Daniel Carl Solander was an 
associate of Linnaeus but it is not clear whether, by placing Solander’s name after the remarks Linnaeus 
was suggesting that he was the author of the species or whether he was merely quoting Solander in 
stating that the species occurred in England. All subsequent authors who have referred to the “‘ Sys- 
tema Natura ’’ have attributed the name spinosa to Linnaeus. 
