532 PKOCEEDINGS OF THE GEOLOGICAL SOCIETY. [JunO 17, 



the delicate common tube. It was found by Prof. Harkness, some 

 years ago, in the Upper Llandeilo rocks of Dumfriesshire, at Duff- 

 kitinel Burn near Wamphray, and it forms, therefore, another of 

 the many Dumfriesshire species which are found also in the Conis- 

 ton Plags. 



Loc. Coniston Flags of Mosedale in Long Sleddale. 



Genus Geaptolites, vel Geaptolithtjs, Linn, 



In describing the species of the genus Graptolites there are some 

 terms which it is as well to define beforehand. Theoretically each cel- 

 lule may be looked upon as a cylindrical tube, possessing in longitudi- 

 nal section four borders. Of these, the " inner" is not defined, as it 

 forms the base of the cellule, and rests upon the common canal ; the 

 "outer" border forms the cell-mouth; the "inferior^' margin is 

 that which bounds the cellule proximally or towards the base ; and 

 the "superior^' is that which forms the distal limit. In many 

 species, such as G. Sagittarius, Linn., all these are present. In some 

 Graptolites, however, the superior margin of the cellule may be said 

 to be practically absent, as in G. Nihsoni, Barr., and G. discretus, 

 Xich., since in these cases the cellules are triangular, and the com- 

 mon canal is the limit along both the inner and the superior mar- 

 gins. In others, again, as in G. Sedgwichii, Portl., the cellule ter- 

 minates in a pointed apex, so that the outer margin can hardly be 

 said to form a distinct line. 



Geaptolites lobieeeits, M'Coy. PL XIX. figs. 27-30. 



G. lohiferus, M'Coy, Ann. & Mag. Nat. Hist. 2nd series, vol. vi. 

 p. 270, and Pal. Poss. pi. 1. B. fig. 3. 



G. BecH, Barr. Grapt. de Boheme, pi. 3, figs. 14-18. 



6r. Nicoli, Harkness, Quart. Journ. Geol. Soc. vol. vii. pi. 1. 

 figs. 5 a, h. 



G. Clitigani, Carruthers, Geol. Mag. vol. v. pi. 5. figs. 19 a, h. 

 Stipe linear, monoprionidian, often of great length, and attaining 

 a breadth of from ^^ to -J^- of an inch in the fully grown por- 

 tion. Axis slender and hair-like. Common canal broad and well 

 marked. Cellules nearly rectangular to the axis, but having a 

 slight upward inclination ; their upper margins curved, termina- 

 ting in " obtusely rounded lobes," in which " a notch on the un- 

 der edge separates the rounded extremity from the oblique descend- 

 ing margin" (M'Coy). The cellules in the fully developed portion 

 of the stipe vary between 12 and 30 in the space of an inch, the 

 average in the Dumfriesshire specimens being from 16 to 18, whilst in 

 the examples from the Coniston Flags it is from 20 to 30. The base or 

 proximal extremity is slender and curved, the common canal having 

 a great comparative width (see PI. XIX. fig. 29) ; the cellules are 

 from 20 to 25 in the space of an inch, and are much narrower than 

 those in the adult portion of the stipe, coming to bear a considerable 

 resemblance to the cells of G. SedgivicJcii, Portl. The ceU-mouth, 

 as is occasionally well shown, opens at the notch in the under mar- 

 gin of the cellule (PI. XIX. fig. 30). 



