Lign. 51. Mantellia cylindrica.
(Brongn.); 1/8 nat.
(Cycadites microphyllus. Bd.)
Wealden. Petrified Forest of the Isle of Portland.
The other species is subcylindrical, and the leaf-scars are much smaller and more regular than in M. nidiformis, indicating a more delicate foliage, as expressed by Buckland's specific name: that of M. Brongniart refers to the cylindrical form of the stem. This plant was higher and more slender than its associate. Numerous buds are seen in the axillæ of the petioles in the specimen figured.
These fossils present, both externally and internally, a close relation to the bulbiform stems of the recent Cycadeæ, named Encephalartos, of South Africa.[132]
[132] The fossil Cycads of the Isle of Portland are admirably described and illustrated in Dr. Buckland's Bridgewater Essay, (p. 497, and pl. lx. lxi.), and their internal structure is fully explained.
Neither the leaves nor the fruit are known: a cone found in the Dirt-bed of Portland, and attributed to these plants, appears to belong to the coniferæ of the petrified forest. Examples of Mantelliæ have been found in the quarry of Portland-stone at Swindon, Wilts.
CLATHRARIA LYELLII.
