1873.] 



Plants of the Coal-measures. 



397 



which has its surface prolonged into a number of very long radiating 

 spines. This fruit the author unhesitatingly identifies with the aerial 

 stems previously described. 



He then examines various so-called VoTkmanniaz found in the Lan- 

 cashire Carboniferous shales, of which the internal structure is not pre- 

 served, but which, being found with leaves attached to them, admit 

 of no doubt as to their belonging to Aster ophyllites. These are re- 

 garded as being identical with Volkmannia Dawsoni ; hence the author 

 accepts the latter fruit as giving the internal organization of the ordinary 

 Asterophyllitean strobilus. The fruit, which has been previously described 

 by Binney, Carruthers, and Schimper, under the names of Calamodendron 

 commune, Volkmannia Binneyi, and Calamostachys Binneyana, is then in- 

 vestigated. The above authors had associated it with Calamites ; but 

 its internal structure is shown to have nothing in common with that 

 type ; it consists of alternating verticils of barren and fertile appendages. 

 The former are nodal disks bearing protective leaves ; the others are 

 verticils of sporangiophores, usually six in each verticil, and which closely 

 resemble those of the recent Equisetacese ; they project at right angles 

 from the central axis, and expand at their outer extremities into shield- 

 like disks, which sustain a circle of sporangia on the inner surface of 

 each shield. The sporangia consist of a very peculiar modification of 

 spiral cells ; they are filled with spores which have been described as 

 provided with elaters, like those of Equisetum ; but the author rejects 

 this interpretation, regarding the so-called elaters as merely the torn 

 fragments of the ruptured mother cells in which the true spores have 

 been developed. The vascular axis is shown to be solid, and without any 

 cellular elements, being wholly different from that of Calamites, in which 

 the vascular axis is a holloiu cylinder containing an immensely large, 

 cellular, and fistular pith. In one fine example of Calamostachys Binney- 

 ana the author has found the central fibro-vascular bundle surrounded by 

 an exogenous ring. This, too, exhibits no resemblance whatever to the 

 corresponding growths of Calamites ; on the other hand, it corresponds 

 closely with conditions occurring in some parts of Asterophyllites, with 

 which group the author believes the fruit to be related, notwithstanding 

 the peculiarity of its sporangia and sporangiophores. The author is 

 confirmed in his conclusion that this fruit is not Calamitean by his 

 having already described the structure of a true Calamitean strobilus, 

 from an example in which the central axis retains most accurately the 

 arrangements of tissues characteristic of Calamitean stems (Manchester 

 Transactions, 1870). A type of stem to which the author had pre 

 viously assigned the provisional generic name of Amyelon is now shown 

 to be the root or subterranean axis of Asterophyllites, specimens being 

 described in which clusters of rootlets are given off, in irregular order, 

 from various points of the exterior of the branching roots. The latter 

 have no medulla ; but in the centres of several of them the author 



