396 SCIENCE PROGRESS. 



read before the Royal Society by Williamson and Scott, on 

 the genera Catamites, Calamostachys and SphcnopJiyltum. 

 In a prefatory note to this memoir, Professor Williamson 

 writes in the following words : "My morphological inquiries 

 seem to have reached a stage that makes a more minutely 

 careful examination of these questions of development and 

 growth desirable ; but before specially undertaking this, I 

 saw clearly the extreme importance of doing so in com- 

 bination with some younger colleague whose familiarity 

 with the details of the physiology of living plants was 

 greater than my own. Under these circumstances I have 

 secured the co-operation of Dr. D. H. Scott, and the 

 present paper embodies the results of our united investiga- 

 tions." This first instalment under the joint authorship 

 gives an extremely lucid and thorough description of 

 Catamites and Sphenophyllum, and in addition to working 

 into a complete whole the scattered contributions by 

 Williamson and others on the morphology of these plants, 

 there are several new and important facts embodied in the 

 memoir, which is illustrated partly by photographs, and 

 partly by a series of admirable camera lucida drawings by 

 Mr. Brebner. 



The Calamite, as usually found in Upper Carboniferous 

 shales and sandstones, occurs in the form of straight or 

 curved and tapered specimens, with regular transverse 

 constrictions marking the position of the nodes ; the inter- 

 nodes are traversed by longitudinal ribs and narrow grooves 

 which generally alternate in position from one node to the 

 next. In most specimens there is a small oval or round 

 protuberance at the upper end of each internodal ridge, 

 giving the appearance of a series of small scars immediately 

 below each node. These are the casts of the " infranodal 

 canals " of Williamson ; by some writers regarded as the 

 points of attachment of leaves or roots, but now usually 

 interpreted as the casts of canal-like spaces which extended 

 through the primary medullary ray tissue of the plant. A 

 specimen figured by Williamson in 187S 1 shows the tapered 



1 Williamson (3), pi. xxi., fig. 31. 



