INTERNODES OF CALAMITES. 497 
OssERvATIONS by Mr. Francis Lewis on Calamitina varians, 
var. inconstans. 
This specimen, which is in the Ravenhead Collection, Liverpool Museum, 
has been fully described by Kidston * under the name of Calamitina varians, 
Sternb., var. inconstans, Weiss. The specimen measures about 32 em. in 
length, and shows two complete and two incomplete periods. —Kidston's 
deseription does not contain any reference to variations in the shape or size 
of leaf-scars in different parts of the same period. He describes the Jeaf-scars 
as transversely oval or sub-triangular, and mentions a note by Dr. Weiss, 
Berlin, that the sub-triangular form of the leaf-scars may be the result of 
pressure bringing about a slight distortion. 
An examination recently made by me of all the clearly defined leaf-scars 
in this specimen shows that certain variations in size and shape do occur in 
different regions of the same period. 
The two complete periods exhibited by this specimen were examined and 
the 1еаЁ-зсатз drawn with a Zeiss camera lucida under а magnification of 8. 
Owing to the variation in shape of the scars, and. the fact that in some cases 
the margin is not very clearly defined, it is difficult to express the variations 
in figures, but the changes in shape and size are shown in the accompanying 
figure ( Fig. 1). 
The leaf-scars in the lower period show a gradual increase in size from 
the whorl next above the lowest branch-scar up to the 6th and 7th nodes. 
From here a slight decrease takes place, the leaf-scars of the 11th node 
being smallest, and the scars of the 12th node at the end of the period being 
slightly larger. 
In the upper period the changes are more definite. The 1st node in the 
2nd period shows small leaf-scars ; from here the size rapidly increases, 
reaching a maximum at about the 5th node. The 6th node shows slightly 
smaller sears, the 7th, 8th, and 9th are nearly of the same size, but the 18th 
and the 11th at the end of the period show a rapid decrease in area, the 
ТИВ next below the branch-sear being the smallest. 
* Trans, Roy. Soc. Edin. vol. xxxv. p. 891, 1890. 
