Parts of the Lantern of Aristotle in Echinus miliaris. 477 



Text-Fig. -2. Text-Fig. 3. 



Text-Fig. 2. — Reconstruction of a fairly advanced tooth as viewed from the inner side. 

 R.T., Root-end of the tooth where the lamellae can be seen in all their progressive 

 stages; CP., Calcareous particle, the first beginning of a lamella; F., Flange; 

 L., Lamellae: 2L.C, Two lamellae in the process of cone-formation; 2Z.C", A 

 fully formed cone ; BK., The beak of a cone ; L.T., Lower part of the tooth where 

 the walls of the cones have fused ; M., Mesh-work formed by the coalescence of 

 lamellae ; P.P., " Pars petrosa," or the stony part. 



Text-Fig. 3. — Actual drawing of a tooth less advanced than the one shown in text- 

 fig. 2, viewed from the outer side ; the first cone is still intact ; it will be noticed 

 that the cones are yet imperfect on the outer side, fusion between the edges 

 thereof being considerably delayed ; F.C., First cone ; P.P., the " Pars petrosa," 

 or the stony part resulting from the union of the apices of the serially fitting 

 cones ; 2L.C, Two lamellae in the process of cone -formation ; L., Lamellae ; 

 CP., Calcareous particle ; O.E., Outer edges not yet approximated. 



