Mr Lapworth on the Genus Nemagraptus (Nematolites). Ill 



Of the systematic position and the probable alliances of 

 this strange group of fossils it is at present extremely hazardous 

 to conjecture. I would suggest, however, that they are 

 possibly the remains of the creeping stolons of some sertu- 

 larid hydrozoon, or the like. It is clear that they are not 

 Bhdbdopliora or true Graptolites. The absence of anything 

 like carbon in the fossil is decisive upon this point. They 

 occur also in incredible multitudes in beds from which Grap- 

 tolites are altogether absent. 



We cannot, it is true, be absolutely certain that our 

 British forms belong to the same genus as Emmons's Nema- 

 graptus cajpillaris ; but if his figure and description of this 

 species are reliable, its generic identity with the Arenig form 

 from St David's is highly probable. In view, however, of 

 the doubtful character of Emmons's type species, and of the 

 undoubted distinctness of our British examples from the true 

 Graptolites, it becomes a matter of necessity to avoid the use 

 of Emmons's title of Nemagrapius for these forms. I propose 

 to substitute the parallel title of Nematolites, by which I have 

 usually designated them in the field. 



Nematolites (gen. nov.) {—'INemagraptus, Emm.). 



Polypary(?), compound, net-like, consisting of numerous 

 filiform and apparently smooth branches, dividing dichoto- 

 mously, or throw^ing off at irregular intervals similar secondary 

 branches, which anastomise and form an irregular network. 



The whole of the forms known to myself are very similar 

 in their general aspects, and it is by no means easy to decide 

 upon the characters which may serve to separate the different 

 species. The main points of distinction appear to be the 

 greater or less tenuity of the branches, their comparative 

 remoteness, their greater or less flexibility, the varying angle 

 of their divergence from each other, and the form and size of 

 the resultant meshwork. 



Three forms will here be noticed, which appear sufficiently 

 distinct for specific titles. The first is characteristic of the 

 Upper Caradoc rocks of Girvan, the second is peculiar to 

 the Skiddaw slates, and the third is present in the Upper 



