492 



MISS G. L. ELLES ON THE GRAPTOLITE [Aug. 1 898, 



Salt., and a third on a slab which also bears D. gibherulus, Nich., 

 and Phyllograptus typus, Hall. These fossils are all characteristic 

 of the highest beds of the Swedish Phyllograjptus-skifliiv, from which 

 horizon I have also seen a form of Tetragraptus similar to that 

 just described. 



Locality. — Barf, near Keswick. 



(e) Teiragraptijs Postlethwaitii, sp. nov. 



This species belongs to what may be called the ' fruticosus-type ' 

 of Tetragrajpti. ' Rhabdosoma pendent ; all the stipes directed 

 vertically or obliquely downwards, narrowest at their origin, but 

 widening somewhat rapidly to a maximum width of Jg- inch (1*58 

 mm.). Thecae : long narrow tubes of uniform width, numbering 

 between twenty-eight and thirty to an inch (eleven to twelve in 

 10 mm.) ; inclined at about 30^, with very slight concave curvature, 

 and in contact for the greater part of their length. Apertures 

 nearly straight, making an angle of about 130° with the general 

 direction of the stipe.' 



The species is large, and the stipes often attain considerable 

 length; in one specimen a length of 3| inches (88-7 mm.) has been 

 measured, but the width remains constant at -^ inch (1*58 mm.) 

 throughout the whole length. 



The dorsal walls of 

 the stipes are com- Fig. 14. — Tetragraptus Postlethwaitii, 

 monly curved. All sp. nov. (colls. Postlethwaite and 



details of the proximal Woodwardian Mus.). 



end are obscure. 



The species differs 

 from Tetragrajptus fru- 

 iicosus (Hall) : (1) in 

 the absence of gradual 

 widening ; (2) in the 

 lower angle of inclina- 

 tion of the thecae and 

 the greater number in 

 a given unit of length. 



It differs from T, 

 pendens^ sp. nov. : (1) 

 in its much larger size ; 

 (2) in the higher angle 

 of inclination of the 

 thecae and the greater 

 number in a given unit 

 of length. 



Some aspects of T, 

 quadribrachiatus pre- 

 sent a similar appear- 

 ance, and from this 

 form it may be distin- 

 guished by the charac- 

 ters of the thecae. 



[A, B, C= typical forms from Carlsicle Edge; 

 D=a specimen doubtfully referable to this 

 species, from Barf. All are shown of the 

 natural size.] 



