OF LOWER GREENLAND PLANTS. 29 



1909. Bennettites Gibsonianu-s, Scott, Studies, vol. 2, pp. 560 et seq., 



text-figs. 200, 202, 203, 204, 205. 

 1911. Bennett ites Gibsonianus, Wi eland, Amer. Journ. Sci., ser. 4, 



vol. 32, pp. 133 et seq., text-fig. 2. 



Diagnosis. Trunk 20 -f? cm. high and 28x16*5 cm. in 

 diameter (the elliptical compression petrifact ?). Leaf-bases 

 rhomboidal, 3-4 cm. x 2-2'5 cm., tangential!) 7 extended; total- 

 ling 7-10 cm. in thickness in transverse section of the trunk. 

 Meristele a curved and infolded horseshoe of mesarch, collateral 

 bundles. Fructifi cat ions 5 cm. long, 2'5 cm. in diameter, en- 

 closed in sheathing bracts, each with 3 vascular bundles. Pith 

 10x2*5 cm. Woody axis of main trunk broken by large 

 curved leaf-traces, which run straight out to the leaf-bases. 

 A single cambium gives rise to rather irregular radial series 

 of tracheids. Tracheids all scalariform, up to 40x38/u in 

 diameter. Large quantities of phloem in which single thick- 

 and thin-walled elements alternate. Pith, cortex, and leaf- 

 traces, as well as scale-leaves, are all composed of a large- 

 celled ground-tissue with numerous gum-canals. 



Cones numerous, embedded between leaf-bases, about 2-5- 

 3 cm. in transverse section. In the cone the expanded re- 

 ceptacle measures about 10 x 12 mm. Interseminal scales vary 

 up to 3*5 cm. long. Seed-stalks roughly circular, 1-2 mm. in 

 diameter. Seeds, when apparently ripe, measure 3x2 mm. up 

 to 4x2-5 mm., not including the length to the tip of the 

 rnicropyle from the shoulder of the seed. Testa three-layered, 

 the central stone composed of one or two thick-walled cells. 

 Seeds exalbuminous. Embryo massive, 5-6 vascular bundles 

 in each of ib? two cotyledons. 



The diagnosis originally given by Carruthcrs (1870, p. 700) 

 is as follows: "Trunk compressed elliptical, with small 

 medulla and a thick subcontinuous woody cylinder ; vascular 

 bundles passing almost directly outwards and breaking up into 

 a double series of small bundles, which are parallel to the 

 superior and inferior surfaces of the petiole, except that a loop 

 is sent down from the upper series into the centre of the petiole. 

 The section of the petiole is subquadrangular." 



HOEIZON. Lower Greensand. 



LOCALITY. Luccomb Chine, Isle of Wight. 



