AZYGOGRAPTUS. 95 



the stipe tliey are in contact only, but tliey may 



H.—Azygogmplus Hicksii, '- "^ _ _ . . 



Hopkinson. ovei'la}) for One tliird of tlieir length in the distal 



portion. The apertnral margins are straight or 

 slightly concave, and according to preservation may 

 Distal thoca\ whitosand Bay. Coll. a])]X'ar perpendicular or oblique. 



Woodwardian Museum. . ^ . . ... 



Affinities. — Az. HicJcsii somewhat resembles Az. 

 Lapworthi in the mode of origin and curvature of its stipe ; it can, however, be 

 readily distinguished from that form by its longer and more distant thecse. The 

 curvature of the stipe, and its mode of origin, also distinguish it from the tAvo other 

 known species, Az. coalehs and Az. suecicus. 



RemarJcs. — This form, originally described by Hopkinson as a Tetragraplus, is 

 a well-marked Azygograptus. We refigure the type specimens (PI. XIII, figs. 2 

 a — c), and it will be seen that the apparent branching is due to the accidental 

 association of several stipes, the direction of the tliecse showing that they belong to 

 several individuals. In the specimen figured by Hopkinson as 12 c and 12 d, the 

 structure at the termination of the stipe, which looks like a fragment of another 

 stipe, is the sicula ; and in addition to the forms figured by him, there are several 

 well-preserved specimens in the same collection in which the proximal end is com- 

 plete. It is a characteristic habit of this form that several individuals should occur 

 together in more or less tangled confusion. 



Horizon and Locality. — Middle Arenig (of Hicks). 



St. DavicVs District : Whitesand Bay. 



Associates, etc. — Azygograptns Hiclsii has not yet been found associated with any 

 other fossils. All the specimens known to us come from the Middle Arenig rocks 

 of "Whitesand Bay. They were collected by Hicks and Hopkinson, and by them 

 were presented to the Woodwardian Museum. 



Group II. — Type Az. suecicus. 



Azygograpti in which the stipe generally grows rigidly outward and down- 

 ward; and, originating slightly above the aperture of the sicula, is appressed to the 

 latter for a short distance ; the thecse are long and narrow, and the amount of 

 overlap is small. 



Azygograptus suecicus, Moberg. Plate XIII, figs, o a—ii. 



1891. Azyyograjitus succims, Moborg, Geol. Foreia. Forliaudl.. vol. xiv, p. 342, pi. viii, figs. 1 aud 2. 

 1898. Azygo/j/rajdus suecicus, Elles, Quart. Jouru. Geol. Soc, vol. liv, \>. 514, fig. 29. 



Stipe rigid or with very slight curvature, 1 — 4 cm. in length, of a uniform 

 width of -8 mm., growing straight downward from the aperture of a 



13 



