506 



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



width lying between yL and ^ inch (2-5 and 2-1 mm.), but in the 

 larger specimens referred to above the width is as much as i inch 

 (3-17 mm.). 



Fig. 22. — Didymograptus patuhis, reverse aspect ; from 

 Handed Crag, coll. Woodiuardian Museum. 



[Nat. size.] 



The thecsB number twenty-four to the inch (nine to ten in 10 mm.) 

 as a general rule, but twenty-six or twenty-eight (ten to eleven in 

 10 mm.) may be counted near the proximal end. They are 

 inclined at various 



angles in different parts Fig. 23. — A portion of the same, shovnnrj 

 of the stipe: near the origin of th.l^.th.P, a7id connectiny-canal. 

 proximal end they are 

 inclined at about 45°; 

 a little farther away 

 from the sicula the}' 

 curve so that, while 

 the inclination at their 

 bases is only 25°, their 

 apertures make with 

 the general direction of 

 the stipe an angle of 60°. 

 The thecse are 3 times L ^ ^'^ 



as long as wide, and are free for about a quarter of their length. 



The apertures of the thecse are concave and submucronate, and are 

 inclined at a constant angle of about 130° in the mature part of the 

 stipe: it is characteristic of the species that the anterior msa'gin 

 of each theca is vertically above the base of the second theca in 

 advance. The thecse usually show lines of growth parallel to their 

 apertures. 



Occurrence. — With Didymograptus gihherulus, Mch., and 

 Azygograptus suecicus, Moberg, in the Middle Skiddaw Slates. 



Localities. — Large specimens, and all the best ones, from 

 Randal Crag ; others from Outerside, Aik Beck, and Carlside Edge. 



(/) DlDTMOGElPTTTS GEACILIS, Tomq. 



1890. Didymograptus gracilis, Tornq. ' Undersokn. of v. Siljausomradets Grapt.' 

 pt. i, Luuds Univ. Arsskrift, vol. xxvi, p. 17 & pi. i, figs. 9-12. 



There can, I think, be no doubt that a specimen in Mr. Postle- 

 thwaite's collection should be referred to this graceful little form. 



The species is extremely slender, and it is characteristic that 

 the stipes appear to diverge from the sicula at markedly different 

 levels. In the light of recent research this must mean that the 



