6 JURASSIC RHYNCHONELLIDS 
result of referring to figures and descriptions which were inadequate in the first 
place. In 1920 Leidhold published a paper in which he proposed the genus Septali- 
phoria and two subgenera within it, namely Thurmannella and Blochmannella. 
Although the descriptions of the type species were inadequate, the names Septalt- 
phoria and Thurmannella have since been widely used as a result of the lack of 
generic names at this level. 
Probably the most notable contribution to the subject was Wisniewska’s (1932) 
monograph on the Upper Jurassic rhynchonellids of Poland. In that work she pro- 
posed the genera Monticlarella, Lacunosella and Septocrurella and in publishing the 
first transverse serial sections of many of the rhynchonellids of this age made a major 
advance in their study. The use of transverse serial sections was well known to 
several authors of the last century, notably Bittner and Rothpletz, but the tech- 
nique was allowed to lapse until its use by Wisniewska and its application was not 
widely publicised until Muir-Wood’s paper in 1934. In common with virtually all 
the other works previously mentioned, Wisniewska gave no details of lithology or 
associated fauna and very little information about relative abundance and distribu- 
tion. 
Since Wisniewska, the only major work devoted to the Upper Jurassic brachiopods 
has been Makridin’s (1964) study of the faunas of the Russian Platform. In this 
work Makridin was seriously handicapped by a lack of comparative material from 
the classic areas of N.W. Europe and, as a result, many of his assignations and con- 
clusions are considered to be doubtful. Brief diagnoses of all the Mesozoic genera 
are to be found in Makridin (1960) and Ager (19650). The ecological aspects of the 
Mesozoic brachiopod faunas have recently been discussed by Makridin (1964) and 
Ager (1965). 
Il. ECOLOGY 
The environments colonised by the rhynchonellids during the whole of the Meso- 
zoic were discussed in detail by Ager (1965a). In that paper seven different habitats 
were recognized namely : (1) very shallow water sea floors, (2) sublittoral, sand 
grade sea floors without reefs, (3) sea floors in the vicinity of reefs, (4) shallow, non- 
depositional sea floors, (5) sublittoral, mud-grade sea floors, (6) deeper (? bathyal) 
mud-grade sea floors, (7) floating weed, and the adaptations shown by the Mesozoic 
brachiopods to each of them described. Within the area described by the present 
author, however, not all these environments appear to be present as the region was 
largely covered by a relatively shallow shelf sea. As far as they have been eluci- 
dated, the environments colonised by the rhynchonellids during the Upper Jurassic 
in northwestern Europe are as follows : 
(a) Sandy, near-shore environments. 
This facies is well developed in the lower and middle Oxfordian around the northern 
rim of the Paris Basin ; a similar environment was also present in much the same 
area during lower Callovian times and, while this is strictly outside the strati- 
graphical limits of this study, it is discussed for comparison. The formations 
representing this environment at these times were the “ Terrain a Chailles”’ and 
ce 
