NICHOLSON SKIDD AW GRAPTOLITES. 143 



to the axis; the whole presenting a strong resemblance to some 

 forms of Oraptolites tenuis, Portl. 



Dendrocjrapsus ficrcatula, Salt., founded on some small fragments 

 from the Lower Llandeilo rocks of Wales, appears at present to be 

 undistinguishable from this species. 



Loc. Bai-ff, near Keswick ; EUergill Beck, near Milburn in West- 

 moreland. 



III. Appendix. 



Since the foregoing has been written, Prof. Harkness has kindly- 

 placed at my disposal some specimens which he has recently dis- 

 covered near Crummock, and which appear to contain two new 

 species. I have likewise obtained from Mr. Joseph Graham, of 

 Keswick, a species of Tetragrapsus, which seems to be new to 

 Britain. Subjoined is a short description of these, as complete as 

 the materials at present obtained will allow ; and I have added a list 

 of all the Graptolites as yet recognized as occurring in the Skiddaw 

 Slates. 



26. DicHOGEAPSTJS RETicuLATTTS, Mcholson. PI. Y. figs. 3-5. 



Spec. char. Frond compound, consisting of a short funicle giving 

 off four main celluliferous stipes, each of which gives origin to two 

 secondary stipes at angles of from 60° to 90°. There are no secondary 

 stipes to each main branch further than these two ; nor is there 

 any reason to believe that; these in turn give off tertiary branches, 

 though it is possible that such really exist. The first secondary 

 branch is giren off at a distance of about i of an inch from the 

 funicle, the second at from 1- to J of an inch from the first. Both 

 the primary and secondary branches run in straight lines, being 

 monoprionidian, narrow at their commencement, but ultimately ex- 

 panding to a width of from J^ to jL- of an inch. The cellules are ex- 

 tremely badly preserved, and it is impossible to say how near to the 

 funicle they may commence. In some fragments, apparently refer- 

 able to this species, they are narrow, inclined to the axis at an 

 angle of about 20°, with the cell-mouths at right angles to the axis, 

 thus resembling some forms of Graptolites Sagittarius, Linn. The 

 denticles are angular, about 2d in the space of an inch, their apices 

 not produced or mucronate. This very remarkable species exhibits 

 a mode of branching quite unique amongst the Dichograpsi ; but 

 it certainly belongs to the group comprising B. fleocilis, Hall, D. 

 rigidus, Hall, and D. multiplex, Nicholson, and, like them, it has 

 probably never possessed a central disk. It is more closely allied 

 to D. multiplex, Nich., than perhaps to any other ; but it is easily 

 distinguished by the repeated dichotomous division displayed by the 

 latter species. 



Loc. Scale Hill, near Crummock. 



Genus Pleurograpsfs, Nicholson (Geol. Mag. vol. iv. p. 256). 



This genus was originally founded by myself to include those 

 branching and compound Graptolites in which there is no proper 



