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A New AzygograiDtiis from North Wales. 



Thecae 7-5 iu 10 mm., four times as long as wide, simple tubes- 

 of approximately even breadth overlapping |-|- their length ; outer 

 walls straight ; apertural margin even, perpendicular. 



Description. — The stipe is always definitely flexed, though less 

 conspicuously than in Azygog. lajmorthi ; the growth of the earliest 

 thecae resembles somewhat that of Azygog. suecicus, but the 

 aperture of the sicula is, as a rule, freer than in that species, though 

 there is some variation in this respect due to the method of preserva- 

 tion and the effects of compression. The thecae measure 2*5 mm. 

 in length when fully developed, but are shorter than this in 

 the region of the sicula ; their inclination is invaiiably low, not 

 exceedincf 10°. 



Azygograptus eivionicus. 1. Specimen showing " spring " of stipe ; type, 

 2. Proximal end. 3. Distal fragment. All x 5. 



Affinities. — This species approaches Azygog. lapworthi in the 

 curvature of the stipe, but the stipe never springs away directly 

 from the sicula as in that species, and the thecae are of a more uniform 

 breadth throughout their length ; they are also less numerous in a 

 given unit of length and inclined at a lo^wer angle. From Azygog. 

 suecicus this species may be separated by the greater degree of 

 curvature of the stipe and the more distant thecae ; as a rule also 

 the aperture of the sicula is free, which is not the case in Azygog. 

 suecicus. 



Horizon and Localities. — Azygog. eivionicus occurs often in dense 

 " mats " in the Arenig rocks of North Wales in the zone of Diclymog. 

 extensus. It has been found at various localities in the Lleyn 

 peninsula, including Nant, south of Llaneugan, and in the Bangor 

 area, at Garth Pomt, north of Bangor, and at University College Cliff. 



The type specimens are in the Sedgwick Museum, and others are 



