Page:Quarterly Journal of the Geological Society of London, vol. 27.djvu/544

 fibres do not show the longitudinal lines always present in Protospongia major, nor are they flattened ; but in this specimen the fibres are much larger than in the one figured by Mr. Salter in Quart. Journ. Geol. Soc. vol. xx. pl. xiii.

EXPLANATION OF PLATES XV. AND XVI.

(Illustrative of Fossils from the Longmynd Rocks of St. David's.)

Plate XV.

Fig. 1. Head of Plutonia Sedgwickii, Hicks.

1 a. Portion of the same, magnified.

2. Head (small) of Plutonia Sedgwickii.

3. Free cheek of P. Sedgwickii.

4. The same, large size.

5. Margin of the head of a large specimen of P. Sedgwickii.

6. 7, 8. Pleurae and part of the axis of P. Sedgwickii.

9. Paradoxides Harknessi, Hicks, head of.

10. — —, labrum.

11. — —, a thoracic segment.

12. Discina pileolus ? Hicks, from the red rocks at the base of the purple sandstones.

12 a. — —, magnified.

13 and 14. Lingulella primoeva, Hicks.

15, 16, 17. Leperditia? cambrensis, Hicks.

15 a, 16 a, 17 a. — —, magnified.

18. Part of the head of a Trilobite from a bed at the base of the purple rocks, about 3000 feet below the " Menevian group."

Plate XVI.

Fig. 1-4. Conocoryphe Lyellii, Hicks.

5-7. — —, narrower form.

8. — solvensis, Hicks, head of.

9. Microdiscus sculptus, Hicks.

9 a. — —, magnified.

10. — —, tail of.

10 a. — —, tail of, magnified.

11. Agnostus cambrensis, Hicks, head of.

11 a. — —, head of, magnified.

12. — —, tail of.

12 a. — —, tail of, magnified.

13. Theca antiqua, Hicks.

14-17. Protospongia ? major, Hicks, from the Longmynd Rocks, St. David's.

18. — —, from the " Menevian Group," St. David's.

19. Protospongia? flabella, Hicks, from the " Menevian Group," St. David's.

19 a. — —, portion magnified. St. David's.

20. — fenestrata, Salter, from the "Menevian Group," St. David's.

Discussion.

Mr. Hughes bore testimony to the admirable work done by Mr. Hicks, who had, almost unaided, worked out the geology of that district. Allowing that many subdivisions and new specific names had with great advantage been introduced into petrology, he de-