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PLATE 53. 



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Fig. 1. 281. 13. Endocerab MAONivENTatiM. (Pag. 218.) 



1 a. A fragment, showing several of the chambers, with the large siphuncle projecting above. 



1 b. An artificial longitudinal section, showing the proportional diameter of the siphuncle and shell, as well 

 as the extreme convexity of the septa, which are correctly represented as somewhat irregular in this 

 respect 



1 e. A transverse section of the larger extremity, which is worn off obliquely. At d d the outer line indicates 

 the edge of the siphuncle ; the inner one being perhaps an exfoliation from the same, but too obscure 

 to determine its character. At e, the embryo tube, with a young shell, is clearly distinguishable within 

 the siphuncle. The position of the same is shown in the longitudinal section, which slightly cuts its 

 outer edge. 



Fig. 2. Ensoceeas PHOTEiPOBHE. (Pag. 213.) 



A large fragment of this species, in which tlie embryo tube is preserved, while the surrounding shell has been 

 partially removed. 



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