THE AUSTRALIAN HYDROMEDUS^E. 



Part IV.— Plates 12 to 17. 



By Pi. von Lendenfeld, Ph.D. 



THE GRAPTOLITHID^E, PLUMULAKIMI 

 AND DICORYNIDJE. 



6. FAMILY. GRAPTOLITHID^. 



Possessing a chitinous Endo- and Exo-skeleton. The former 

 rod-shaped. Colonies free swimming, probably extinct. From 

 the Cambrian to the lower Devonian. 



I. GROUP. GRAPTOLOIDEA. Lapworth. 

 Hydrosome developed from a Sicula, every canal containing 

 Coenosarc, bears only one row of cells. Axis (Virgula) on the 

 dorsal side, in a furrow of the inner lamina. 



A. MONOPRIONID.E, 

 Hydrothecae in one row opposite the axis. 



1. SUB-FAMILY MONOGRAPTIN^E. 

 MONOGRAPTIDJ3. Lapworth. 

 Developed one-sided; pointed ends of the Sicula pointing 

 upwards, united with the doi'sal margin of the proximal end of a 

 single or composite Hydrosome. 



No Australian representatives of this Sub-family are known. 



