426 



NEW YORK STATE MUSEUM 



Suecoceras marcoui Holm. Geol. For. i Stockholm Forh. 1896. 



18:403, 414 



Barrande has described in his monumental work as Endoceras 

 marcoui (in the explanation of the plate termed "Ortho- 

 ceras" marcoui) a fragment of a cephalopod, which had been 

 collected by Jules Marcou in the Beekmantown beds at Philipsburg 

 and sent to him. We insert here copies of Barrande's original 

 figures [text fig. 9-1 1]. These show us at once that the specimen 

 is one of the interesting inflated apical parts of a conch, for which 



Fit^ Q 10 II Suecoceras marcoui Barrande (sp.) Three views 

 Sf a nepionic bulb. Fig. g^lateral aspect; iig. io=side which 

 approaches the external wall ; fig. ii=transverse section. Nat. size 



the term preseptal cone has been used by Clarke and nepionic bulb 

 by Hyatt and the phylogenetic meaning of which has been discussed 

 by the present writer in another paper [1904]- 



While Barrande, with his characteristic keenness recognized the || 

 very imperfect specimen as belonging to the Endoceratidae and stated 

 that " it is the only specimen in his possession which shows the 

 mitial part of the conch of an Endoceras," he erred in mistaking^ 

 the surface of the fragment for the external surface of the 

 shell and in describing the rings as annulations. They are but 

 the impressions of the septal necks and the fragment is only 

 the inflated apical portion of the siphuncle. The central tube filled 



1 This mistake was more than natural before Holm and Clarke had recog- 

 nized, from more complete material, the actual structure of these apica ^ 

 portions of the conchs. 



