JOURNSL ROYAL SOCIETY, N.S.W., 1888. Pi»tei4 p«tnj 



Fig. 25. Oater surface of Trigonia lamarckii, seen obliquely, x 800 diam. 



1g. 26. Surface of a tubercle on ribs of Trigonia lamarckii, seen obliquely, showing lenses, x 300 diar 



Pig. 27. Surface of the exterior of Trigonia lamarckii, seen obliquely, x 300 diam. 



This kind of surface is generally seen between the ribs and not showing the projecting lenses. 



