86 VINE : BRITISH PALEOZOIC CTENOSTOMATOUS POLYZOA. 
Genus Ascodictyon, Nicholson & Etheridge. 
1877. Ann. Mag. Nat. Hist., ser. 4, vol. xix., p. 463. 
1882. Ascodictyon, Vine, Quart. Journ, Geo!. Soc, Feb., p. 52. 
1884. „ Vine, Ann. Mag. Nat. Hist., Aug., p. 78. 
1890. „ Ulrich, Geol. Survey Illinois, vol viii:, p. 367. 
Zooecia consisting of radially arranged fusiform or bulbus Zocecia, 
or filiform threads with periodic swellings. 
The simple diagnosis which is given above is formulated by 
Mr. Ulrich for his Synopsis of Classification (op. cit., p. 367), and its 
adoption here will enable me to place in the genus the whole of the 
vesicu]ated Zoaria found in the Wealock Shales. The type species, 
A. fttsiforme, Nich. and Eth., of Ascodictyon, is derived from Middle 
Devonian rocks of Ontario (Hamilton formation). 
Ascodictyon filiforme, Vine, pi. Ill, figs. 8-15. 
1882. A. filiforme, Vine, Quart. Journ. Geol. Soc, Feb., pp. 54-55. 
1884. „ „ Ann. Mag. Nat, Hist., Aug., pp. 78-80. 
1887. „ „ Yorksh. Geol. Soc, vol. ix., p, 183. 
Zoarium filamentous, forming linear, contorted, or clustered 
threads, adherent to shells, stems of crinoids, fragments of trilo- 
bites, but rarely to corals. Filamentous threads, hollow, but sur- 
rounded by delicate calcareous walls ; the hollows filled with a 
dark-brown granular mass. Lageme-like divergences developed on 
the sides of the tlneads, sometimes as single vesicles and occasionally 
as groups. Peculiarly clustered stellate fibres are also formed at 
irregular distances. 
Localities and Horizon: Up. Silurian Wenlock Shales; Built Iwas 
beds ; generally distributed in the whole of the Buildwas washings 
but more abundant in the debris, numbered 36 and 38. 
In the papers referred to under the headline A. filiforme I have 
dealt with this peculiar species, and all its variations, rather minutely. 
At the time of writing the last paper mentioned I was inclined to 
adopt the family name Stomatoporidcv (op. cit. p. 183), in which I 
could include both Ascodictyon and Rhopalonaria, chiefly on account 
of the problematic characters of some of the forms described. Since 
then I have pondered much over these anomalous organisms, and I 
