CLIMACOGRAPTUS. 



L93 



a and b. — Climacograpli 

 brcvis, sp. no v. 



third; apertures situated in semicircular excavations, which occupy one 



third to one quarter the width of the stipe, and one third of the ventral 



margin. 



Description. — CI. breiris is a small species; it may attain a length of 1*5 cm. as 



a maximum, but specimens having a length of 1 cm. 



are of commoner occurrence, and the breadth is as 



a rule rather less than 1 nun. The thecal apertures 



are nearly opposite to each other, and the outer 



walls are straight or slightly widened with a 



tendency to rounding off at the base. 



Affinities. — This species is obviously very closely 

 allied to 01. minimus in point of size and in the 

 general characters of the thecas ; its chief distinction 

 lies in the lesser breadth and smaller degree of 

 overlap of the thecas and larger apertural ex- 

 cavations. From all other forms it may be dis- 

 n^Z^d^^onMtSS tinguished by its small size and the characters of 



Gwern-y-fed-facli, Builth ; Llan- j^g f^ango 

 deilo Beds. Coll. Elles. 



Horizon and Localities. — Llandeilo Flags; Glen- 

 kiln and Lower Hartfell Shales ; Dicranograptus Shales. 



8. Scotland: Dobb's Linn ; Hartfell; Mount Benger Burn. Wales: Gwern-y- 

 fed-fach, Builth ; S. of Wolfsdale ; Parsonage Llandewy Velf ry ; Clarbeston Road 

 Railway Station ; Spittal Road Cutting. 



Associates, etc. — CI. breois is a common fossil in the Llandeilo Flags of Gwern- 

 y-fed-fach, near Builth, where it is found on the same slabs as Nemag. pertenuis 

 and Dicellog. sextans. It is also found in the Glenkiln Shales of S. Scotland, and 

 in the Dicranograptus Shales of S. Wales. It appears to belong characteristically 

 to this horizon, but some individuals survive into the Lower Hartfell Shales. 



a. Proximal end, obverse view, showing 



apex of sicula. Enlargement of 

 part of PL XXVII, fig. 2 a. 



b. Small but complete specimen, reverse 



Climacograptus bicornis (Hall). Plate XXVI, tigs. 8 a—f. 



1847. Graptollthus bicornis, Hall, Pal. New York, vol. i, p. 268, pi. lxxiii, fig. 2. 



1870. Climacograpsus bicornis, Nicholson, Aim. Mag. Nat. Hist., ser. 4, vol. vi, p. 380, figs. 5 a, b, c, d. 



1874. Climacograptus bicornis, Dairon, Trans. Greol. Soc. Glasgow, vol. v, p. 183, pi. i, fig. 25. 



1876. Climacograptus bicornis, Lapworth, Cat. West Scot. Foss., pi. ii, fig. 51. 



1877. Climacograptus bicornis, Lapworth, Grap. Co. Down, Proc. Belfast Nat. Field Club, p. 139, 

 pi. vi, fig. 38 a. 



1902. Climacograptus bicornis var. longispina, T. S. Hall, Records Geol. Survey N.S. Wales, vol. vii, 

 pt. 2, p. 5, pi. xii, figs. 8, 9. 



Polypary 2 — (J cm. in length, widening gradually from origin until a 



