CALAMARIEAE. 329 



shows a hollow medullary cylinder and a weakly developed ring of primary 

 bundles, in each of which is a lacuna. Renault says distinctly that he has 

 found tracheal elements only in the immediate neighbourhood of the lacuna. 



Renault 1 has also described two other spikes of Calamostachys as 

 Bruckmannia Grand' Euryi and B. Decaisnei. As they were obtained 

 from sections of the siliceous fragments of Grand' Croix, the details only 

 of their structure are known. The structure of their axes agrees perfectly 

 with that of the form already described from Autun. A remarkable feature 

 is the large number of members both in the fertile and in the sterile whorls, 

 eighteen in the fertile whorls in Bruckmannia Grand' Euryi and twelve in 

 B. Decaisnei, while in the sterile whorls there are twice these numbers. 

 With this agreement between the numerical relations and those of Calamo- 

 stachys Ludwigii, we may assume that there was here the same alternation 

 as in that species. The sporangial leaves have the usual umbrella-like form; 

 they bear four sporangia, as Renault 2 distinctly states 3 and as his figure 

 shows, exactly in the position which they have been described as occupying 

 in Calamostachys Ludwigii ; the upper surface of the umbrella-roof is strongly 

 developed, and reaches to the leaf-whorl next above it and unites with it. 

 A branch of the foliar bundle, which bifurcates twice, runs to each of the 

 sporangia, which are themselves badly preserved. The spores in Bruck- 

 mannia Grand' Euryi lie connected together in fours in their mother-cells, 

 which also unite together in fours 4 . In the sterile whorl the leaves, which 

 cohere below, form the often-mentioned horizontal disk, while their free upper 

 extremities bend sharply over and are directed upwards. There is one circum- 

 stance peculiar to these two species and sharply distinguishing them from the 

 typical forms just described, namely, that each sporangiophore is connected 

 by means of a vertical radial plate of tissue with the basal disk of the leaf- 

 whorl next above it, and thus the sporangia, at least those in the upper 

 row, come to lie in radial compartments, which are open below but are 

 covered towards the outside by the extension of the umbrella-roof. In this 

 way I understand, and I believe correctly, Renault's description, in which 

 there is absolutely no room for assuming the presence close .beneath the 

 sterile whorl of a third whorl from which the plates spring, and which 

 Stur 5 makes the foundation of his interpretation of the structure. 



Renault 6 , who formerly ranked all the spikes which we have been 

 describing with his Asterophylliteae and Annularieae, has very recently put 

 forth the view,. that a part of them belong as male flowers to Arthropitys, 

 and to Calamodendron as he understands that genus. He expressly men- 

 tions Calamostachys Binneyana and C. Grand' Euryi as belonging to this 

 division, and calls their spores directly pollen-grains. He relies in this 



1 Renault (5), tt. 3, 4. 2 Renault (5), t. 4, ff. 8, 9. 3 Renault (5), p. 16. 4 Renault (5), 

 t. 3, f. 5. 5 Stur (5), p. 147 and figures. 6 Renault (17). 



