20 JURASSIC RHYNCHONELLIDS 
DISTRIBUTION. The genus occurs most commonly in the Swabian and Franconian 
Jura ; outside those areas it has only definitely been recorded from Poland and the 
French Jura and in both these regions it is a very scarce form. Makridin (1964) 
does not record it from the Russian Platform, although it is stated to occur there in 
the Russian “‘ Treatise ”’ 
OccURRENCE. The three species investigated in detail all have consistently well 
developed pedicle openings which, it is reasonable to assume, indicate a functional 
pedicle in the adult stage. This latter fact, coupled with the wide distribution of the 
species and the fact that they can occur in a variety of high energy environments, 
suggests that the mode of life could well have been one of attachment either to 
sponges or floating material. This hypothesis would account for the diversity of 
environment in which the genus occurs. 
Monticlarella czenstochaviensis (Roemer) 
(Pl. 1, fig. 4, text-fig. 8) 
1870 Rhynchonella Czenstochaviensis Roemer: 247-48, pl. 22, figs. 12-14. 
1917 Rhynchonella Czenstochaviensis Roemer; Rollier: 116. 
1932 Monticlarella czenstochowiensis (Roemer); Wisniewska: 57-58, pl. 6, figs. 13-18. 
EMENDED DIAGNosIs. Medium sized, subtriangular Monticlarella ; maximum 
width well toward anterior margin ; valves equally biconvex or with the pedicle 
valve the more inflated ; rectimarginate ; test covered by fine cee striae ; con- 
centric growth lamellae may be present ; crura arcuifer. 
STRATIGRAPHICAL RANGE. Lower Oxfordian—cordatum zone. 
TYPE SPECIMEN. Lectotype, here selected, the specimen figured by Roemer 
(1870) pl. xxii, figs. 12-14, from “‘ Clarenberges ’’ near Czenstochowa, Poland. 
MATERIAL. 5 specimens collected by Dr. D. A. B. Pearson from the Holy Cross 
Mts., Poland. 2 specimens obtained by Dr. D. V. Ager from the type locality. 
DIMENSIONS OF FIGURED SPECIMEN. 
length thickness width 
I-02 cm 0-73 cm I-'I3 cm 
9 
JQOO0008 
MONTICLARELLA CZENSTOCHOWIENSIS (Roemer) 
Oxtfordian, Poland. J.1219/2 
Fic. 8. Transverse serial sections of Monticlarella czenstochaviensis (Roemer) kindly made 
available by Dr. D. V. Ager. Numerals represent distance in millimetres from pedicle 
umbo. 
