370 



THE OSTRACODERMS. 



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Fig. 249. — Photograph of a small group of Bothriolepis. The individual, a, after death, came to lie hac^mal 

 side up, on what was the bottom at that time; its dorsal fin and tail lie in a horizontal plane. Individuals, b and c. 

 died in their natural position; that is, buried in the mud, h;"emal side down. Their dorsal fins and tail lobes are 

 in a nearly vertical position. 



Fig. 250. — Photographs of Eothriolepis, seen from the haemal surface, showing:; the conspicuuus membranous frills 

 surrounding the cxhalent opening.' of the atrial chamber. 



