Observations on the ornamentation and ultra-structure of some well preserved, specimens of ldiognathoides noduliferus inaequalis Higgins (Pennsylvanian conodont)

Examination of specimens of Idiogllalhoic/es Iloc/u/((el"l/s il/aequalis from the Panching limestone (Pennsylvanian) of Pahang. Peninsular Malaysia with a scanning electron microscope reveals well developed striations on the denticles of the blade. One of the specimens, broken to reveal the internal structure, shows that in the posterior part of the platform apatite crystallites are aligned with their c axes perpendicular to the lamellae whereas crystallites in lamellae of the blade denticles are oriented irregularly. The upper surface of the unit is seen to have a thick outer single layer ofapproximately IOjlm thickness enveloping alternating thin lamellae (I jlm) and interlamellae spaces. The interlamellae spaces are best developed in regions of active growth (ie. along axes of blade denticles).