296 MR. W. D. LANG ON GROWTH-STAGES [ Mar. 2, 
the Paris example that the two specimens are specifically identical. 
‘To save further confusion the specimen at hand, B.M. no, 48412, 
is considered here as the holotype of P. fittoni; and the specific 
determination of the Paris specimen must be settled when an 
opportunity of examining it occurs. I wish to express my thanks 
to Dr. Kitchin, of the Museum of Practical Geology, and to 
Professor Boule, of the Muséum d’Histoire Naturelle, Paris, for 
their kindness in supplying me with information in this matter. 
Text-fig. 41. 
PARASM/LIA FIT TON Edwards 
& Haime. 
D* 
RESUVENESCENCE. 
— REJUVENESCENCE. 
g 
5 
s 
REJUVENESCENCE. 
J 
[ee REJUVENESENCE. 
O REJUVENESCENMCE, 
Ss om RESUVENESCENTCE. 
eee Gin 
Sn  / PEDUNCLE 
STAGE. 
Costal stages in P. fittoni Edwards & Haime. 
Type-specimen, B.M. no. 48412. X 14 (Peduncle restored.) 
In the forms hitherto considered, the costal growth-stages have 
been easy to follow, because the ornamentation of the costa has 
regularly followed the changes in its general shape. Six stages 
have been demonstrated covering two periods—the Plain and 
Ktched Periods; so that the stages have been termed Low Plain, 
Medium Plain, High Plain, Low Etched, Medium Etched, and 
High Etched. With P. fittoni a new type of ornamentation is 
introduced—the granular ornament, and with it a new period of 
costal elevation, But so dominant is the granular ornamentation 
in P. fittoni, that instead of first appearing with a low wide costa, 
