Chap. VII.] 
FOSSILS OF THE LOWEE LUDLOW. 
127 
need not be figured here. Some remarks on the principal species will be given 
at the end of this Chapter. 
The Starfishes, some of which are here delineated (Foss. 21), are considered 
to belong to genera, perhaps to families, distinct from any living forms. One of 
them, Palseocoma (figs. 3, 4), resembles, indeed, certain living rare forms of 
Starfish (Pteraster) in the great length of the spines, which, however, are 
longer in the fossil than in the living genus. Palasterina, M'Coy, is more like 
the Palmipes roseus. Others (Protaster, figs. 1, 2) have the general form of the 
OphiuraB or Brittle-stars, to which they are allied, but differ in the number and 
arrangement of the component plates of the skeleton. No less than ten species 
of Starfishes have already been found here j and new forms of great beauty are 
occasionally discovered. 
• Fossils (21). Starfishes of the Lower Ludlow Eock. 
(See also Foss. 57, for other Upper-Silurian Starfishes.) 
1, 
2 
3. PalaeocomaMar- 
stoni, Salter. 
4. P. Colvini, id. 
These are Star- 
fishes allied to 
Palmipes and 
Pteraster. 
Among the Orthocerata, the largest, and perhaps the most common, are Ortho- 
ceras Ludense, PI. XXVIII. f. 1, and 0. filosum, PI. XXVII. f. 1 ; these are gene- 
rally accompanied by a smaller, thin-shelled species, which appears to be the 
O. subundulatum of Portlock. The others, though often found, are by no means 
so abundant or characteristic. Of Lituites, the only common species is a very 
large one, eight or ten inches in diameter — the L. giganteus of PI. XXXIII. f. 1, 
2, 3. The Phragmoceras, above noticed, is a remarkable shell, with the mouth 
or opening contracted into the shape of a key-hole. Some of its forms are flat- 
tish, broad, and shaped like a hatchet-head (PI. XXXII.) ; whilst others, known 
as the pear Orthoceratites (PI. XXX.), are suddenly swollen into a balloon-like 
shape above, and end in a tapering point below. 
• Of Lamellibranchiate Shells, Cardiola interrupta, Broderip, is the most com- 
mon (PI. XXIII. f. 12) ; yet the same species, formerly believed to be peculiar 
to this zone, has also been found in the Caradoc formation ! Another Bivalve 
equally characteristic, and as yet known only in Upper Silurian rocks, is the 
Cardiola striata (PI. XXIII. f. 13) ; and, in company with the chambered shells 
above noticed, it is to be found in all the fossil-bearing localities of Shropshire 
and the neighbouring regions. Orthonota rigida, PI. XXIII. f. 8, and Pterinea 
retroflexa, f. 17, are not so common ; and the latter is far more frequent in the 
Upper Ludlow rock. 
Indeed many species of fossils have been obtained both in this stratum and 
the Wenlock formation, especially Brachiopodous Shells. Among these may be 
