Lign. 73. Siphoniæ, from the Greensand; nat.
Wilts, and Isle of Wight.
| Fig. | 1.— | Siphonia pyriformis; the body or upper part. |
| 2.— | Vertical section of the same, showing the internal structure, and the central cavity. | |
| 3.— | Specimen of S. pyriformis in a young state. | |
| 4.— | Siphonia (Polypothecia, of Miss Benett,) lobata; Firestone or Upper Greensand, Warminster. | |
| 5.— | The lower part of the stem, and radicles, of S. pyriformis. |
A group of Sponges from the Upper Greensand, near Warminster, figured and described by the late Miss Etheldred Benett,[210] under the name of Polypothecia, comprises several forms that are allied in structure to the Siphoniæ. These fossils present considerable diversity of shape; one of the lobed forms is delineated in [Lign. 73, fig. 4]: and a branched species in [Lign. 74]. Upon breaking the stem of one of these zoophytes transversely, sections of parallel longitudinal tubes like those in the Siphoniæ are exhibited.
[210] An elegant Memoir on the Wiltshire Fossils, by this accomplished lady, is published in Sir R. C. Hoare's "Wiltshire."
Lign. 74.
Polypothecia dichotoma.
Upper Greensand, Warminster, Wilts.
The Kentish rag contains irregular ramose spongeous bodies, which belong to this group of porifera; and Mr. Bensted has discovered in his quarry, near Maidstone, numerous remains of a polymorphous lobed zoophyte, having a porous structure beset with spicula. In the Firestone of Southbourne, Steyning, and Bignor, in Sussex, I have observed large pyriform and subcylindrical Siphoniæ.