358 PALEONTOLOGY OF ILLINOIS. 



From whatever point the question may be viewed, no one can 

 deny the relation between the genera as here outlined. As re- 

 gards the relation generally supposed to exist between Acantho- 

 cladia and Thamniscus, my investigations have convinced me 

 that it has no real foundation in nature. That the branches in 

 the two genera are free is of little consequence, since there are 

 differences of far greater import. In fact, Acanthocladia is con- 

 structed upon the same plan as Pinnatopora Vine (Glauconome 

 of authors), Synocladia King, and Septopora Prout. In these 

 four genera comprising the bulk of the ACANTHOCLADIIDJE, as 

 here denned, the zoarium consists of primary and secondary 

 branches, the latter being smaller and arranged in a pinnate 

 manner on each side of the former. In the two first the second- 

 ary branches are never united, bnt in Synocladia and Septo- 

 pora, those which spring from adjacent primary branches coalesce 

 so as to produce a reticulated expansion. 



As Mr. G. R. Vines arrangement of the Bryozoa under consid- 

 eration is quite different from that adopted by me, it is but 

 justice to the student that some mention be made of it. He 

 restricts the family FENESTELLID^E to fenest rated or non-fenes- 

 trated forms in w T hich the zocecia are "arranged biserially in 

 the branch." The four genera Fenestella, Ptilopora McCoy, 

 Pinnatopora and Septopora, he groups under this head. The 

 new family DIPLOPORID^E he proposes for the reception of Diplo- 

 pora, Acanthopora and Actinostoma, three genera previously 

 proposed by Messrs. Young and Young as subgenera of Fenes- 

 tetta and Glauconome. For Polypora and Phyllopora King 

 he proposes the POLYPORID^E. Lastly, Kings family THAMNI- 

 SCID.E, containing Thamniscus, Acanthocladia and Ichthyorachis 

 McCoy, is accepted by him. 



This classification is so obviously artificial that the proba- 

 bilities are very much against its acceptance by any one who 

 will undertake an extended study of the forms in question. His 

 definition of the FENESTELLID.E would include Phylloporina daw- 

 soni, and the Permian Phyllopora ehrenbergi since in both the 

 zocecia are arranged in two series. What would he do with 

 such forms as Polypora whitei, P. radialis, P. biserialis, P. 

 celsipora Hall, P. art a Hall, and P. incepta Hall? They would 



