62 JURASSIC RHYNCHONELLIDS 
that while many of the specimens were in “ nests ”’ or associations, either vertical or 
horizontal, many others occurred singly and scattered through the rock unit. The 
above mentioned “ nests ’’ have been referred to by Ager & Evamy (1963) as seeming, 
“to be true colonial associations ”’. 
( 
0-5 
0:3 
46 42 
Transverse serial sections of Acanthothiris cf. costata Orbigny. Bathonian/Cal- 
lovian. Middle Chanaz Beds. Pugieu (Ain), France. (4). 
