species o/" Didymograpsus. 341 



niciits,' at p. 5G3 (fig. 656), and by some oversight named I), 

 (jcminus, 11 is., is also really I). p<i(nhis. 



Loc. Skiddaw Slates of ( )uteiside, near Keswick, and Egg- 

 beck, near Pooley ; Lower Ijlandcilo, west ot" the Stiperstones. 

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

 Quebec group of Canada.) 



Didymograpsus V-fractus^ Salt. 



(Quart. Journ. Geol. Soe. 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 i\Ir. 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- 



Didymograpsiis V-fractus, after Salter. Skiddaw Slates. 



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

 are l)ent 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 aj.*e abso- 

 lutely undistinguishable from D. jMfulus, Hall. I should 

 therefore be disposed to think that the form cannot be regarded 

 as more than a variety of D. pafuhis, unless this charactei" 

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

 amples. 



Loc. BarfF, near Keswick (Skiddaw Slates). 



Didymograpsus extensus^ Hall, sp. PI. VII. figs. 2, 2 a. 

 GraptoUthus extensus, Hall (Grapt. Quebec Group, p. 80, pi. 2. figs. 1 1-1(5). 



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 anuular and pointed, but not nmcro- 



Ann.ii' Mag. N. Hist. Ser. 4. Vol.\. 24 



