366 SCIENCE PROGRESS. 



being largely characterised by the possession of eight, four, 

 two stipes and one stipe respectively. In a recent paper 

 by Professor Nicholson and the present writer (15) we 

 have endeavoured to show that this is not the case, but 

 that the character of the hydrothecae and to a less degree 

 the amount of angle of divergence of the stipes are of im- 

 portance. We endeavour to prove that certain grapto- 

 lites underwent development along parallel lines, passing 

 through many-branched, eight-branched, four-branched, 

 two-branched and one-branched forms, thus illustrating the 

 principle of heterogenetic homoeomorphy advocated by 

 Mojsisovics, S. S. Buckman and others. If this be allowed, 

 many of the present genera will have to be abolished and 

 new ones formed ; but the writers earnestly advocate the 

 retention of the present genera under existing circum- 

 stances, and hope that the formation of fresh genera will 

 be deferred until our views are more fully developed or 

 perchance disproved, though we do not think that the latter 

 event is likely. 



It will be noticed that the above researches into the 

 morphology of the graptolites deal mainly with the 

 celluliferous portions of the polyparies, whilst the study of 

 the various bodies referred to as concerned in reproduction 

 has not been largely pursued of recent years. 



Passing now to the memoirs treating of the graptolites 

 as indices of age of the rocks which contain them, it may 

 be remarked at the outset that recent work has fully estab- 

 lished the correctness of the views advanced by Lapworth 

 in his papers on the Moffat series and on the geological 

 distribution of the Rhabdophora. Perner alone has stood 

 out for the anomalous occurrences described by the eminent 

 Barrande in the Bohemian basin, but he does not yet 

 appear to have studied completely the zonal distribution of 

 these organisms in that region, though he has added largely 

 to the number of species occurring in the Lower Palaezoic 

 rocks of Bohemia. The new species described here and 

 elsewhere of recent years it is not contemplated to notice in 

 this article, though they will doubtless give us much 

 information in addition to that we have already obtained 



