148 Prof. T. R. Jones and Dr. H. Woodward— 
and more solid form, being probably true gastric teeth; and (2) a 
compressed trenchant type, being a portion of the true mandible. 
Some, indeed, of the European forms also may have belonged to this 
latter type; but, as the bases (if ever existent) have been broken off 
in the Gothland examples, and hidden in the figures of those from 
Bohemia, we are unable to speak with confidence as to this part of 
their structure. The differences, moreover, in the material in which 
they have been imbedded, and in the conditions of pressure and 
fossilization, may have modified the organisms to a very consider- 
able degree. 
oa 
zy) 
Specimen ‘45160’ in British Museum. From Lesmahago. Nat. size. 
Specimen ‘“ 4/136”’ in Cambridge Museum. From Lesmahago, Nat. size. 
Specimen “58878”’ in British Museum. From Lesmahago. Nat. size. 
Specimen ‘‘6/11” in Cambridge Mus. From Beck Mills, Kendal. Nat. size. 
Part of specimen “ 47989’ in the British Museum, showing the position 
of the ‘‘ teeth” in the anterior region of the carapace of Ceratiocaris 
papilio. From Lesmahago, Lanarkshire. Nat. size. 
We cannot pretend to refer these fossil teeth to the known species 
of Ceratiocaris ; but evidently there are six different forms ; thus :— 
1. With neatly chevron-shaped cusps, regular in size. Woodcut, Fig. 2, Barrande’s 
pl. 18,2: 2 (2); pl. 21,1. 41-44; and Pl. VI. Fig. 8. 
2. Small neat cusps, longer at one end of the tooth than at the other. Woodcuts, 
Figs. 5, 6, 7, 8 (£), 9. 
3. Cusps with a more flexuous connecting ridge. Pl. VI. Figs. 10 a, 10 3, 10 ¢. 
4. OCusps in two parallel rows, but somewhat alternate. Barrande’s pl. 31, f. 21. 
5. Cusps irregularly alternate in two rows. Woodcuts, Figs. 3 and 4. 
6. Cusps ina single row. Pl. VI. Figs. 9 a, 9 0. 
Note.—It may be well to mention that in the “‘ Quart. Journ. Geol. 
Soe.” vol. xvii. 1861, pp. 542-652, pl. 17, Dr. J. Harley described 
and figured numerous small, waterworn, organic fragments from the 
Ludlow Bone-bed, under the generic name of Astacoderma; and he 
referred them to a Crustacean origin, mostly as being morsels of the 
harder parts of tests and limbs, but in two instances as having some 
resemblance to ‘‘ the stomach-teeth of the common Lobster ” (p. 550, 
pl. 17, figs. 11-18). In “Siluria,” 8rd (called the “ 4th”) edit. 
1867, p. 542, it was suggested that all the specimens figured by Dr. 
Harley, excepting figs. 15 and 16, were really portions of the teeth 
of Phyllopod Crustaceans such as Ceratiocaris. 
