514 MISS G. L. ELLES OK THE GEAPTOLITE [^^^g* 1 898, 



biifc it gradually increases in width up to a maximum of ^-^ inch 

 (1*05 mm.). Ths stipe may be as much as 2 inches (50-7 mm.) long 

 and is alvrays concavely curved. 



Locality and Horizon. — Hodgson How Quarry, near Portin- 

 scale (Middle Skiddaw Slates). 



(V) AZTGOGRAPTUS COELEBS, Lapw. 



1880. Azygograptus ccelebs, Lapw. Ann. Mag. Nat. Hist. ser. 5, vol. v, p. 159 

 & pi. V, figs. 16 a-c. 



Bhahdosoma unilateral, consisting of a single stipe, which is very 

 slightly curved and appears to originate from the major extremity 

 of a small but clearly defined sicula. The stipe runs in a direction 

 perpendicular to the long axis of the sicula. 



The thecse number twenty-five to the inch (ten in 10 mm.) ; they 

 are narrow tubes expanding slightly in the direction of the aperture, 

 inclined at an angle of 15^. Outer wall with very slight concave 

 curvature. Thecae in contact for a short distance at the base; some 

 of the earliest developed thecae ma}^ be in contact for as much as 

 one-third of their length. The apertures of the thecae are acute, 

 straight, and face slightly inwards. 



The sicula is well marked though small, -gL inch ('87 mm.) 

 long ; it is wider than in Az. Lapwortlii. The earliest theca 

 appears to arise at the base of the sicula on the right, at least that 

 is the point at which it curves away from the sicula ; but from the 

 structure it seems that it actually originated at a point considerably 

 higher up the sicula, and grew closely adpressed to the sicula until 

 near its aperture, when it took a sudden curve outwards. Perhaps 

 this was to give greater strength of attachment to the sicula, 

 which, as I have shown, is frequently broken off in Az. Lajpwortki 

 at the point of connexion with the stipe. 



Lapworth states the maximum length of the stipe as 2 inches 

 (50'7 mm,), but none of the specimens that have come under my 

 notice have exceeded ^ inch (12-7 mm.) in length. The maximum 

 width is -^-^ inch (about '5 mm.) ; there is no marked increase from 

 the point of origin. 



Locality and Horizon. — Ellergill= Upper Skidd aw Slates. 



(c) Azygograptus stjecictjs, Moberg. (Fig. 29, p. 515.) 



1892. Azygograptus suecicus, Moberg, Geol. Foren. Stockh. Forhandl. vol. xiv, 

 p. 342, pi. viii, figs. 1 & 2. 



Rhabdosoma simple, consisting of one slightly curved stipe 

 which originates in the angle between the aperture and the side of 

 the sicula. The stipe makes with the conspicuous sicula an angle 

 of 145°. 



The cells number eighteen to the inch (seven in 10 mm.) ; they 

 are long narrow tubes, in contact with each other for a short 

 distance at their base, but in the more distal part of the stipe they 

 may be in contact for as much as one-third of their length ; they 



