94 



NEW YORK STATE MUSEUM 



The axis or "virgula" of the Axonophora has been currently consid- 

 ered as a solid body until Wiman [1895] observed that it is a hollow con- 

 tinuation of the sicula in Diplograptus and the present writer [1895, pi. 2, 

 fig. 6] finding a specimen of Glossograp'tus quadrimucronatus 

 in which a solid rod (Wiman's virgula, which forms in the wall of the sicula) 

 had been forced out of the tube during the process of compression, con- 

 cluded that the solid axis of the sicular wall extended into the proximal tube. 



34 



Fig. 31,32 Glossograptus ciliatus Emmons. 

 Dilatations of nemacaulus. x 5 



35 



Fig. 33-36 Climacograptus parvus Hall. 

 Dilatations of nemacaulus. x 5 



A contribution was published last month by A. Schepotieff (,1905, 

 p. 79 ff) in which it is shown, by means of thin sections, that the "virgula" 

 of Monograptus priodon consists of a hollow tube with a central 

 solid rod [see text fig. 38, 39"]; and thereby verified the writer's observation 

 in regard to Glossogr. quadrimucronatus. The question arises 



