j"o?"nalfST°lb™!'] Jioijal Microscopical Society. 151 



linear series that their adjoining margins touched, while in the bifur- 

 cated specimen figured on page 148, the lower and older portion is 

 seen to be destitute of them, yet they appear on the two branches. 



We know nothing of the upper portion of Uloclendron. It is 

 very probable that the stems were repeatedly divided in a dicho- 

 tom.ous manner, and that the branches, foliage, and fruit agree so 

 nearly with those of Lepidodendron, that they have been referred to 

 that genus. Hugh Miller, in an interesting paper " On some Fossils 

 from the Edinburgh Coal-field," read to the Eoyal Physical Society, 

 describes a specimen which, as it lay in the rock, exhibited a true 

 branch shooting out at an acute angle from the stem, intermediate 

 between the rows of scars. Unfortunately, the specimen was some- 

 what injured in lifting it from its matrix. It forms part of the 

 Miller Collection now deposited in the Edinburgh Museum. On 

 examination, I found that the leaf scars of the branch were arranged 

 in a direction opposite to those on the stem, but this may have arisen 

 from the fractured specimen having been incorrectly united. 



Bothrodendron is universally referred now to TJlodendron. It 

 was based upon a specimen from which the leaf bases and the 

 outer portion of the stem (/, g, h, of Fig. 1, Plate XXVII.) had been 

 removed, and instead of the more or less rhomboidal scars, the pits 

 of the vascular bundles only are seen. 



Megaplujtum is based upon casts of the interior of the stem 

 against the inner surface of the regular prosenchyma of the stem 

 (e, of Fig. 1, Plate XXVII.). The scar represents only the main 

 central vascular bundle of the scar of TJlodendron, and has the 

 same form in the difi'erent species as in the species of that genus. 

 Thus M. distans agrees with U. StoJcesii, and M. approximatum 

 with U. parmatum. The interrupted striae which cover the stem 

 between the rows of scars are the impressions of the meshes in the 

 prosenchyma, through which the vascular bundles passed to the 

 leaves. This view of these points is further established by the 

 figure of Megaphytum approximatum given by Lindley and Hutton, 

 'Fossil Flora' (plate cxvi.). In this plate a more external portion 

 of the stem is seen on the upper left-hand corner of the specimen ; 

 and this shows the regularly-arranged dots characteristic of the con- 

 dition to which these authors gave the name Bothrodendron. 



Megaphytum is related in the same way to Bothrodendran and 

 TJlodendron, as Knorria is to the " decorticated " and " corticated " 

 forms of Lepidodendron, and as the fluted casts of Calamites are to 

 the smoother "corticated" forms. 



Synopsis of the British Species. 

 Nat. Ord. Lycopodiace^. 



TJlodendron, Lindl. and Hutt., ' Fossil Flora,' plate v. Stem 

 covered with rhomboidal scars of leaves, and having large round or 

 oval conical depressions arranged in linear series on opposite sides, 



