Dr. H. A. Nicholson on new Sjjecies of Graptolites. 239 



and narrower form, and differs still furtlier in the characters of 

 the cellules. 



Loc. Upper Llandeilo rocks of Dobb's Linn, near Moflfat. 



Climacograj^sus tuberculatus^ Nich. PL XL tig. 18. 



8])ec. char. Frond diprionidian, from half to over three- 

 quarters of an inch in length, and of a breadth of about one 

 line in the fullj developed portion. The base is pointed, and 

 is provided with three strong tapering spines or mucronate 

 processes, of which the central one is the smallest and consti- 

 tutes the true radicle, whilst the two lateral ones arc nearly 

 rectangular to the axis, and are slightly curved tow^ards their 

 extremities. The cellules are about thirty in the space of an 

 inch, excavated in the substance of the frond, and appearing 

 in a scalariform specimen as linear or elliptical apertures ex- 

 tending across the stipe. Between the rows of cellules on the 

 two lateral surfcxces of the frond, the test is fm-nished with a 

 linear series of tubercles or outward processes of the periderm, 

 which are sometimes square, sometimes more or less triangular 

 in shape. One of these processes arises from, or in the imme- 

 diate vicinity of, the lateral angle of each cell-aperture. 



This form is allied to C. hicoruis. Hall, but is clearly sepa- 

 rated by the lateral tubercles, as well as by the nearly hori- 

 zontal position of the tw^o lateral spines at the base. 



Loc. Rare in the Upper Llandeilo rocks of Dobb's Linn, 

 near Moffat. 



Graptolites argenteus, Nich. PI. XI. fig. 19. 



Spec. char. Stipe simple, monoprionidian, commencing 

 proximally in a delicate curved base, and then proceeding in 

 a nearly straight line. Base extremely slender, the cellules 

 having here very much the character of those of G. Nilsso>u\ 

 except that their apices are reflexed. They are long, narrow, 

 and triangular, about eighteen in the space of an inch, the 

 entire length of this ])ortion of the stipe being about four-tenths 

 of an incli. From this point the stipe gradually Avidens, until 

 a breadth of as much as oiie line may be reached ; but this does 

 not appear to be exceeded. The cellules in the adult portion 

 of the stipe are very closely set (from forty to forty-five in the 

 space of an inch), long, narrow, overlapping, one another for 

 more than two-thirds of tlicir entire length, and having their 

 apices reflexed. The basal portion of the cellules is a little 

 wider than the month ; and the length of a full-grown cellule 

 is about a line, the Avidtli not exceeding one-fortieth of an inch. 

 In the distal portion of the stipe the apices of the cellules are 



17* 



