298 CALAMARIEAE. 



in the way of getting together any great number of cases of the kind. 

 Longitudinal sections directed with a view to such minute details are pre- 

 carious, and to this must be added that they are of value only where the 

 sculptures of the cell-walls are perfectly preserved, which is seldom the 

 case. But with all this I still have no doubt but that in the lacunae or in 

 the tissue which fills them we are dealing with the tracheal initial strand of 

 the primary bundle. Apart from this portion the xylem-wedges, according 

 to the accordant testimony of Unger 1 , Goppert 2 and Renault 3 , consist 

 essentially of rows of scalariform tracheides, and with these, according to 

 Renault, are several rows of pitted elements. The medullary rays will be 

 noticed again by-and-by. In the preparations before me I find only sca- 

 lariform vessels, but I have in fact seen sections in the British Museum, in 

 which both forms were present connected by intermediate forms. Annual 

 rings, which might have been expected where the ring of wood is sometimes 

 of unusual thickness, as much as a foot thick, are never seen ; the wood 

 seems everywhere uniform, only tangential fissures or local displacements 

 through pressure, such as often occur, might to a hasty glance have the 

 appearance of rings. It is this absence of annual growth, as well as the 

 peculiar broad bordered pits in single rows which make me suspect, as 

 I have already said, that the wood described by Goppert 4 as Protopitys 

 Buchiana from the Culm of Glatzisch-Falkenberg in Silesia belongs to the 

 present group. 



The wood of all Calamitae has not only the interfascicular but also 

 numerous secondary rays. These differ considerably from one another, 

 but they are all strikingly distinguished from those of Coniferae, as Renault 5 

 has pointed out, by having their elements prolonged in the direction of 

 the axis of the stem, not in that of the radius, as in the latter group. We 

 have no exact information as to the nature of the pitting, and indeed the 

 structure generally of these woods urgently requires further searching 

 investigation. The interfascicular rays also show unusual multiplicity 

 of structure. Cotta 6 himself was struck by these variations in character, 

 and employed them to distinguish the species striata and bistriata in his 

 genus Calamitea, and these were afterwards raised by Goppert 7 to the rank 

 of genera, and named Calamodendron striatum and Arthropitys bistriata. 

 Brongniart's name, which originally included all calamitoid stems with 

 secondary growth, is thus confined to a particular type of them, and 

 Goppert's nomenclature was then adopted by the French school, which 

 treats the two genera as members of the family of Calamodendreae. The 

 two types can usually be readily distinguished even on the simply polished 

 surface of a section, for in Arthropitys the primary rays disappear towards 



1 Unger (9). a Goppert (3), p. 179. * Renault (13). * Goppert (12), p. 252, 



t. 36 and (4), p. 229, tt. 37, 38. 5 Renault ;13 . Cotta (1). 7 Goppert (3). 



