4 JURASSIC RHYNCHONELLIDS 
Although most of the species described have been previously figured, this is the 
first attempt to give such a comprehensive account of these faunas and to clarify their 
synonymies. It is interesting to note in this connection that the French literature 
abounds with Orbigny and Lamarck species, the German with those of Schlotheim, 
Oppel and Quenstedt while many British authors have relied on Sowerby and 
Davidson. By making a palaeontological study on a wider geographical basis than 
is usually attempted, it is hoped to reduce the number of species confined by national 
boundaries. It is considered that the other major justification for attempting to 
study a group over a relatively wide geographical area is that in considering evolu- 
tionary lineages this helps to eliminate any local distortion caused by migration and 
the general imperfection of the fossil record. 
Although essentially work has been confined to taxa within the Upper Jurassic, 
certain species and genera from lower stratigraphical levels have been investigated 
where this was thought necessary. The type species of Acanthorhynchia, namely 
A. panacanathina, from the Bajocian has thus been included and similarly a study 
was made of Acanthothiris spinosa in order to determine the justification for splitting 
the spinose forms into separate genera. 
Previous research 
Although no previous author has attempted to produce such a comprehensive 
monograph of this group of rhynchonellids, there have been numerous descriptions 
and figures published over the last two hundred years. As there are relatively few 
rhynchonellids in the British Upper Jurassic rocks, most of the works referred to are 
by continental authors. 
Linnaeus (1767) described only one of the species discussed below, namely Acan- 
thothiris spinosa ; this species was also the subject of the first figure to which 
reference is made, Knorr and Walch (1769). This appears to be the only recognisable 
eighteenth century description of a Middle or Upper Jurassic rhynchonellid. Of the 
workers of the early part of the nineteenth century, the most important were 
Schlotheim (1813, 1820), Zieten (1830-33) and, to a lesser extent, Lamarck (1819). 
The paucity of British Upper Jurassic material meant that the Sowerbys figured 
only one species—T orquirhynchia inconstans. Fischer de Waldheim’s paper of 1809 
must also be mentioned as this introduced the genus Rhynchonella. The major 
nineteenth century French work was undoubtedly d’Orbigny’s (1850) ‘“‘Prodrome ”’, 
but this lost much of its potential value through lack of illustrations. 
From about 1850 until the beginning of the present century several eminent 
palaeontologists produced many of the monographs still regarded as standard works. 
These writers included Davidson, who described and figured all the then known 
British brachiopods, Eudes-Deslongchamps, who produced numerous well illustrated 
papers on the brachiopod faunas of Normandy and elsewhere and Loriol and Haas 
who produced similar comprehensive works on the French and Swiss Jura. Many 
of the monographs of these authors set standards which have seldom been surpassed. 
Mention must also be made of the writings of Quenstedt (1851-52), which culminated 
in his magnificent work ‘“‘ Die Brachiopoden ”’ (1868-71), still the most complete 
