1852.] STRICKLAND LUDLOW BONE BED. 9 



it as " a layer of fish-bones and pebbles in a loose blackened state," 

 but though it is evidently a drifted deposit, I did not succeed in 

 finding pebbles in it. It is literally a bone-bed, the great bulk of 

 the deposit consisting of osseous and coprolitic matter, mingled with 

 a very small proportion of sand and mud, barely enough to cement 

 it together, and apparently containing no erratic fragments except a 

 few marly nodules. Some portions of it have the appearance of a 

 coarse brown sandstone, but on close examination it is found that the 

 apparent grains of sand are really the so-called teeth of Thelodus par- 

 videns, Agassiz (Silurian System, pi. 4. f. 34, 35, 36), which compose 

 its entire substance. These curious little bodies, composed of two 

 flattened pieces connected by a narrow neck, and which in form much 

 resemble a common shirt-stud, are considered by Agassiz to be the 

 teeth of a fish, though it appears to me not unlikely that they may 

 be the placoid scales, and not the teeth, of the animal. It would be 

 difiicult otherwise to account for the extraordinary profusion of this 

 minute organism, which forms by far the most abundant fossil of the 

 Ludlow Bone-bed, wherever it occurs, and in this locality constitutes 

 the principal bulk of the stratum. 



The only other ichthyic fossils which I have noticed at this locality 

 are the striated spines of Onchus tenuistriatus, Agassiz (Sil. Syst. 

 pi. 4. f. 58). 



Coprolites are abundant in the deposit. They are usually much 

 rolled and water-worn, presenting but little regularity of form, though 

 from their organic contents and the phosphate of lime which they 

 contain*, there can be no doubt as to their nature. 



The following Molluscous remains occur here, either imbedded in 

 masses of coprolite, or in the form of casts filled with coprolitic 

 matter : — 



Orbicula rugata, Sow. Sil. Syst. pi. 4. f. 47, 48. 

 Lingtda cornea. Sow. Sil. Syst. pi. 4. f. 49. 

 Tnrho ? 



Bellerophon expansusi. Sow. Sil. Syst. pi. 4. f. 50. 

 Orthoceras semipartitum. Sow. Sil. Syst. pi. 4. f. 52, 53 ? De- 

 tached casts of chambers with the siphuncle lateral. 



At Gamage Ford, as at Hagleyf, rolled masses of carbonaceous 

 matter accompany the animal remains. These are in the state of 

 coal, and usually present no trace of their original structure. There 

 are however some remarkable seed-like bodies evidently identical with 

 those before noticed at Hagley and at Prior's Frome. They are 

 usually of an almost perfectly spherical form, and present no trace of 

 any point of attachment to the parent plant. Their diameter varies 

 from O'l to 0*2 of an inch. The surface when in a perfect condition 

 is very smooth. 



On breaking open these globular bodies, a central cavity is seen, 

 which is in some cases empty or filled with mineral matter ; in others 

 it contains a powdery carbonaceous substance in which no organiza- 



* See ' Silurian System,' p. 607, for the analysis of those in the Bone-bed at 

 Ludlow. ' t Loc. cit. p. 382. 



