Text-fio. Oa. Text. -fig. 6 b. Text. -fig. 6 c. 
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J. GRAHAM KERR 
Text-figs. 6 A, B, c, D, E, F. — Views of under-siirface of head in Protopterus of stages XXXI, XXXII, XXXIV — , XXXI\ , 
XXXV and XXXVI — , to sliow the relations of the olfactory organs. In e and p the floor of the buccal cavity has been 
partially cut away. c. o. Cement organ, e. g. External gill. olf. Olfactory rudiment, olj. a. and o?/. p. Anterior and 
posterior nares. op. Operculum, to. Tooth. 
