species o/" Didymograpsus. 341 



ments,' at p. 563 (fig. 656) , and by some oversight named ]). 

 geminus, Ilis., is also really D. patidus. 



Log. Skiddaw Slates of Outerside, near Keswick, and Egg- 

 beck, near Pooley ; Lower Llandeilo, west of the Stipcrstones. 

 (Also in the Lower Graptolite schists of Sweden, and the 

 Quebec group of Canada.) 



Didymograpsus V-fractus, Salt. 



(Quart. Journ. Geol. Soc. vol. xix. p. 137, fig. 13 e.) 



This species, of which I subjoin a cut taken from Mr. Salter's 

 figure, was originally named by Mr. Salter from a specimen 

 obtained from the Skiddaw Slates. Mr. Salter, however, 

 never gave any description of the species, so that, unfortu- 

 nately, it is hardly possible at present to decide positively as 

 to its value. My own collection includes a few fragments, 

 but no perfect specimen. The character upon which the spe- 



Fiof. 2. 



Didymograpsus V-fractus, after Salter. Skiddaw Slates. 



cies was founded is the peculiar curvature of the stipes, which 

 are bent abruptly outwards at the distance of about a quarter 

 of an inch from the radicle. The fragments in my possession 

 exhibit this character, but in all other respects they are abso- 

 lutely undistinguishable from D. p)(ituliis, Hall. I should 

 therefore be disposed to think that the form cannot be regarded 

 as more than a variety of D. patuhis, unless this character 

 can be shown to be constant in a considerable number of ex- 

 amples. 



Loc. Barff, near Keswick (Skiddaw Slates). 



Didymograpsus extensuSj Hall, sp. PI. VIL figs. 2, 2 a. 

 GraptoUtkus extensus, Hall (Grapt. Quebec Group, p. 80, pi. 2. figs. 11-lG). 



Frond composed of two long slender stipes diverging at an 

 angle of 180° from a small radicle. The stipes attain a length 

 of several inches without showing any signs of a termination. 

 They have a breadth of about one-fiftieth of an inch close to 

 the radicle, and not more than one-fifteenth of an inch at the 

 distance of three inches from the radicle. Cellules twenty-four 

 in the space of an inch, making with the axis an angle of 

 about 45° ; the denticles angular and })ointed, but not mucro- 



Ann. & Mag. N. Hist. Ser. 4. Vol. v. 24 



