OCULAR AM) (JKMTAI. IM.VIl ,- 



and here consider the several forms from the Pacific and A.laM.i, M all n-f-ral,!,. , r to, 

 In this species we find most interesting characters in nwin | , ((( , 1 , ;irs , fnr . ]thtgm ^ M 

 stages m development and variation in the adult cov,r th,- whol. ,,. of ehaneton MM in 



in 



OK Off O7 



o t/ o o o / 



TEXT-FIGS. 81-87. Ocular plate arrangement in Mesozoic Ccntrerhinidau. 



81. Pseudodiadema pseudodiadema (Lamarck). Coral Rag, Yonne, France. Diam. 20 mm. R. T. J. Coll., 716. 

 X 8. All oculars insert, typical character. 



82. The same. Corallien, Trouville. G. Boehm Coll., Freiburg i. B. X 4. O.-ular I insert, aprogremive variant. 



83. Magnesia punclvlata (Lamarck). Oxford, Berner Jura. G. Bochm Coll., Freiburg i. B. X about 20. All 

 oculars exsert. 



84. Phymechinus mirabilis Agassiz. Oxford, Bcrner Jura. G. Boehm Coll., Freiburg i. B. X 4. All orulweaert, 

 typical character. 



85. Stomechinus bigranularis Lamarck. Inferior Oolite, Broad Windsor, Dorset. Diain. 47 mm. U. T. J. Coll., . 

 X 4. All oculars exsert, typical character. 



86. The same. Diam. 48 mm. R. T. J. Coll., 715. X 4. Oculars I, V insert, a progmwive variant. 



87. Orthopsis miliaris (d'Archiac). Cretaceous, Lcs Tamarins, Algiers. Diam. 20 nun. R. T. J. Coll., 717. X 8. 

 All oculars exsert, typical character. 



the fossil and recent members of the family. In a very young specimen (text-fig. 88) all the 

 oculars are fully exsert and this early stage may be compared with the adult Jurn-i.- I'-i-udo- 

 diadema (text-fig. 81). In an older specimen (text-fig. 89) the oculars are still all exsert, but 



