UPPER LUDLOW GROUP. 175 
Uprrr Lupitow Rocks, 
1, Mudstones—with calcareous bands, especially near the top. 
2. Bone-bed—an inch to a foot in thickness, 
3. Downton Sandstone. Of the Silurian district; represented by a red rock at Usk, and by “tile- 
stones” in the S. Welch district. 
(The Bone-bed and Downton Sandstone are separately catalogued: but it is not always easy, in the absence 
of the very persistent Bone-bed, to draw the line between them.) 




Case and 5 
Column of Reference to McCor's Names and References; Observations, &c. Numbers and Localities. 
Drawers. | Synopsis: and Figures of Genera, 
PLANTA, 
To the group of Nullipores (and especially to 
the genus Acetabularia) are referred several 
thin calcareous expansions which occur in 
Ludlow rocks, but are particularly charac- 
teristic of Upper Ludlow. True sea-weeds 
are also found, but rarely. The want of 
calcareous matter in the fossils (originally 
abundant) is easily explained, as they occur 
in sandy rock, 


p. 42. [Spongarium Edwardsi, Murch. Sil. Syst. t. 26, 
fig. 12. Siluria, 2nd ed. pl. 12, fig. 3. For 
the type, see p. 42.] 

Gf Pl. 1 8, fig. 14, p. 43. Spongarium interlineatum, McCoy. Oval, | a. 997, Brigsteer, Kendal; 
Ge9 quite regular, a very beautiful fossil, A | a.998, b.56, Benson Knott, 
strong central depression with fine radii, | Kendal. 
and concentric rugw, very regular. 
Ge9 Pl OB, fis) 15, p. 42: Spongarium equistriatum, McCoy. Oval and | a. 996, Benson Knott. 
regular, but with coarse rugw and sharp 
coarse radii. 
Ge9 Pl. 1 8, figs. 16, 17, p. 43. Spongarium interruptum, McCoy. Ridges | a. 999, Spital, Kendal. 
alternately large and small, interrupted 
and irregularly prominent. 

Sponges. AMORPHOZOA, Sponges. 
Gt Pl. 1D, fig. 9. ; 
si Pasceolus Goughii, Salter, MSS. The genus | b. 53, b. 54, base, Benson 

f Cae: 

has been described by Billings from Canada. | Knott. 

