Dr. H. A. Nicholson on new Species of GraptoUtes. 233 



line from the radicle, into two secondary branches, of which 

 one is directed upwards and one downwards. Of these the 

 superior branch appears to give off no tertiary offsets, being 

 directly prolonged into the celluliferous stipe. The inferior 

 branch, on the other hand, gives off two tertiary offsets on the 

 same side, the extremities of the three divisions thus produced 

 becoming celluliferous upon one side. The stipes are ex- 

 tremely slender ; the cellules are about twenty in the space of 

 an inch ] the cell-mouths are at right angles to the back of 

 the stijje, and the denticles are simply angular, and not 

 mucronate. 



This pretty little species is distinguished from all the other 

 members of the genus by its very minute size, by its mode of 

 branching, and by the extreme tenuity of the divisions of the 

 funicle and of the celluliferous stipes. 



Loc. Upper beds of the Skiddaw Slates, Thornship Beck, 

 near Shap. 



Dichograpsus (?) annulaius^ Nich. PI. XI. figs. 4 & 5. 



Spec. char. Frond compound, branching and rebranching. 

 Base unknown. Branches coming off from one another more 

 or less nearly at right angles, often attaining a length of from 

 four to five inches, and preserving a uniform width of about a 

 line. Cellules from seventy to ninety in the space of an inch. 

 The face of every one of the stipes is crossed by a number of 

 transverse, sometimes slightly wavy, ridges, amounting to the 

 above number in the inch ; but the state of preservation of the ' 

 specimens is such that it is impossible to determine Avhether 

 these are the cell-partitions or are the mouths of the cellules 

 shown in a scalariform view. In the former case the direction 

 of the cellules would be nearly transverse to that of the stipes. 

 The margins of the stipes, however, are quite plain and ex- 

 hibit no denticles ; so that the latter view would appear to be 

 the correct one. 



This singular form is recognizable, even in small fragments, 

 by the presence of the above-named transverse ridges, which 

 give the stipes somewhat of the aspect of a ringed wonn. 

 Whichever view be adopted of the nature of these ridges, they 

 unquestionably mark the position of the cellules, which are 

 thus seen to reach the extraordinary number of not far from 

 100 in the space of an inch. The central portion of the frond 

 is not shown in any of my specimens (the best of which was 

 discovered by Mr. Christopherson, of Keswick) ; and it is 

 therefore impossible to fix finally the generic position of the 

 species. Its mode of branching, however, corresponds closely 

 with that of Dichograpsus \ and as this genus has its home in 



