676 



SILURIAN CORALS. 



Alecto serpens, Alex. Brongniart, Tableau des Terr. p. 430. 1829; Steininger, 1831, Me'm. 



Geol. Soc. Franc, t. i, p. 341. PI. XX. f. 9. 1834. 

 Stomatopora serpens, Bronn. Lethsea Geognostica, p. 54. Taf. V. f. 10 a and b. 1835. 

 Formations and localities in England. Wenlock Limestone, Lincoln Hill, Coalbrook Dale; 

 Winslow Mill, Lindels, Fownhope, Woolhope ; Dudley. Upper Limestone of the Ca- 

 radoc Formation ; Prolimoor Well, and Norhury, Salop. 

 Foreign localities and authorities. Shores of the Baltic, Fougt ; Bursvik, Gothland, VLismger ; 

 Eifel, Bronn, Goldfuss, Schlotheim, Steininger; Bensberg, Knorr, Bronn ; Arnsberg, Bronn. 

 Aulopora tubceformis (Goldfuss), PI. 15. f. 8. nat. size, attached to Cystiphyllum cylindricum. 

 Syn. and Ref. Goldfuss, Petref. p. 83. Taf. XXIX. f. 2. 1826. 

 Alecto tubceformis, Steininger 1831, Mem. Soc. Geol. France, t. i. p. 341. 1834. 

 Formation and locality in England. Wenlock Limestone, Benthall Edge. 

 Foreign locality. Eifel, Goldfuss, Steininger. 

 Escharina, Milne Edwards. 



Eschariria? angularis, sp. n. Lons. PI. 15. f. 10. nat. size, 10 a magnified. 



E. encrusting ? disk-shaped, raised around the edge : cells distinct, angular, close together, 

 radiating from a centre, parallel to the surface of the disk ; openings of the cells not perfect. 

 Formation and locality. Wenlock Limestone, Dudley. 



Ptilodictya, g. n. Lons., I7t/Aov, pluma ; Uxtvov, rete. 



Generic Characters. — Thin, elongated expansions, having on each surface small quadrangular 

 cells not convex, which penetrate the coral obliquely, and are arranged with respect to the 

 surface, along the middle of the specimen, parallel to the elongated direction of the coral, but 

 on the sides obliquely from it. Surface, a very thin calcareous crust traversed by slightly 

 raised ridges, marking the boundaries of the cells ; towards the margin the crust thickens, the 

 indications of the cells are less distinct, and at the edge are invisible ; but cells are traceable 

 close to the margin where the crust has been removed; opening of the cells small, transversely 

 oval ? no indication of a central partition parallel to the surface. 



This fossil is considered by Goldfuss to be a Flustra, but it is placed by Milne Edwards 

 among the doubtful species of that genus (2nd edit. Lamarck, t. ii. p. 229.). It differs essen- 

 tially from Flustra in the thickening of the external crust, most probably not preserved in Gold- 

 fuss's specimens. From Eschara it differs in not having a central partition, and in the surface 

 of the cells not being convex, but depressed as in Flustra. I have, therefore, ventured to pro- 

 pose the above name taken from the feather-like arrangement of the middle and lateral cells, 

 and their net-like union. 



Ptilodictya lanceolata, Lons. PL 15. f. 11, 1 1 a to 11c. — 11 nat. size, 11a portion of the same mag- 

 nified twice, 11 b a young specimen, 11c the same magnified 3 times. 



P. Expansion long, narrow, flat, slightly curved longitudinally, and thin gradually diminishing 

 to a fine edge; middle cells narrow, small and about 10 rows ; lateral cells larger and arranged 

 in rows slightly arched from the middle to the edge, the cells themselves placed obliquely both 

 with respect to the middle of the coral and the arch. 



Syn. and Ref. Flustra lanceolata, Goldfuss, Petref. p. 104. Taf. 37- f. 2. 1826, 1833 ; Hi- 

 singer, Lethsea Suecica, p. 104. Tab. XXIX. f. 10. 1837. 



The figures 11 and 11 a. PI. 15. do not exactly agree with those in the above references, but 

 the differences are probably due to the state of preservation not being the same. 

 Formation and locality in England. Wenlock Limestone, Malvern Hills {western slopes of) . 



