OF CALAMITEAN STROBILUS. 249 



meter being ^-^, and its lesser one j^ of an inch. Two of 

 the three internodes had been sliced into sections before I 

 saw the specimen ; but the third, which fortunately hap- 

 pened to be the lowest one of the three, was preserved 

 intact, and is represented in figures i and 2, the former 

 being its lateral aspect, and the latter that of its inferior 

 surface. Externally, each internode of the strobilus has 

 exhibited a series of strongly marked, rounded, longitudinal 

 ridges and furrows, the former being apparently about 20 

 in number, though, owing to the fragment being somewhat 

 injured on one side, I could not count them with exactness. 

 These are invested by numerous closely lapping, thin, 

 membranous, vertical bracts. Each of these bracts appears 

 to have occupied one of the furrows between the ridges, 

 its margins having overlapped, or been in contact with, 

 those of its nearest neighbours along the line of each 

 ridge ; but this point also was not very clear, owing to the 

 exceeding thinness of the bracts and the closeness with 

 which they were in mutual contact. The upper part of 

 the fragment having been cut off in making a transverse 

 section, I could not decide whether these bracts terminated 

 with the upper edge of their own internode, or whether 

 their tips were prolonged over the joint above. 



Fig. 2 represents the concave base of the specimen. I 

 do not believe that this has been the actual base of the 

 strobilus. In all probability there has intervened between 

 it and the common peduncle one small joint. That if not 

 the actual basal segment it must have been nearly so, is 

 shown by the rapid contraction of its outline, inferiorly, 

 when seen in its lateral aspect (fig. i). In the centre is 

 the medullary cavity (fig. 2 a), a cylinder with an internal 

 diameter of about y^^ of an inch. This exhibits no struc- 

 ture, its interior being filled with infiltrated crystalline 

 carbonate of lime. That it was hollow when entombed, 

 and has not lost its tissues through fossilization, is shown 



