234 Dr. H. A. Nicliolson on new S/jectes of GrajjtoUtes. 



the Skicldaw Slates, the position of our form is most probably 

 here. 



Loc. Rare in tlie Skiclclaw Slates of Barrow, near Braith- 

 waite, and of Wath Brow, near Keswick. 



Diphgraj^sus Hopkinsoni^ Nicli. PI. XI. fig. 7. 



8pec. cliar. Frond diprionidian, from half to three-quarters 

 of an inch in length exclusive of the distal prolongation of the 

 solid axis, and having a breadth of from one to one and a half 

 line. Base ornamented with a minute triangular radicle, 

 flanked by two long, curved, setiform processes, many times 

 greater in length than the central mucro. Cellules about 

 twenty-four in the space of an inch, obtusely triangular in 

 shape, terminating in long drawn-out tips or denticles, which 

 are obtusely pointed and are usually slightly bent downwards, 

 but which do not terminate in distinct spines. 



The specimens of this form which had previously come 

 under my notice were confounded by me with D. vmcronatus^ 

 Hall, to which they bore, in the shape of the cellules, a con- 

 siderable resemblance. Having now, however, discovered 

 more j^erfect specimens, in which the base is exhibited, I have 

 been led to alter this opinion. D. Hophinsoni is altogether 

 larger and broader than D. mucronatus^ the cellules are larger 

 and fewer to the inch, whilst the denticles are turned down- 

 wards, and do not terminate in spines. Finally, i). muc7'07iati{S 

 does not possess the long basal spines which are so charac- 

 teristic of J). Hopkinsom. These spines are sometimes of 

 great length (a quarter of an inch in one specimen), and in all 

 their characters they resemble those of Climacograpsns anten- 

 nan'us, Hall, which is a characteristic species in the Skiddaw 

 Slates. I have named this form after Mr. John Hopkinson, 

 who has recently written an excellent paper on the subject of 

 Graptolites. 



Loc. SkiddaAv Slates of Outerside, near Keswick. 



Dip>lograpsiis armafus, Nicli. PI. XI. fig. 8. 



SjyeC' char. Frond diprionidian, varying in length from four 

 lines to more than one inch, exclusive of the distal prolonga- 

 tion of the axis. Breadth, exclusive of the spines, from one 

 to one and a half line. Base obtusely pointed, with a single 

 short radicle. Cellules extremely remote, not exceeding twelve 

 in the space of an inch, and having their apices furnished with 

 broad, tapering, slightly deflexed spines, Aviiich attain the 

 comparatively enormous length of from one to two lines ; so 

 that the breadth of a full-grown specimen, including the spines, 

 may be as much as fi^e lines. 



