Lacustrine Formation of Torryburn Valley. i 3 
Allen says that this seed may belong to a Nitella^ perhaps N. 
megacarpa Allen, as he knows of no Chara with similar nuclei. The 
third row of figures, and the first two figures of the fourth row, 
represent this species as drawn by Dr. Allen, and the forms are 
arranged in ascending geological order from left to right, the oldest 
being to the left in the third row. 
The great bulk of the seeds of Chara found in the deposit belong 
to a species which exhibits considerable diversity in the form and 
markings of the nucleus. I did not find any form of this type 
lower down than the top of No. 25 ; but Dr. Allen has detected it 
in the upper part of 2a and the middle of 25. It would, therefore, 
appear to be limited in the lacustrine clay, to that part which is 
least charged with mineral matter, and even there it is very scarce. 
It seems to have found difliculty in maintaining itself in a habitat 
where C. coronata flourished ; but later in the history of the lake, 
when the clayey sediment disappeared, it became immensely abun- 
dant. The partiality of this species for clear water is very evident 
in its increase and prevalence in the higher part of the lake deposit. 
When G . coronata disappeared from the lower layers of the Lake 
Peat, No. 5, this species immediately took its place, and at the top 
layers of the peat its seeds had become numerous. In No. 6 the 
seeds are quite common, and its prevalence in the lake seems to 
have been accelerated rather than retarded by the spread of the 
Molluscan fauna. This form of nucleus was long-elliptical-oblong 
i with sharp keels or striae, generally about 12 in number, but varying 
j from 10 to 13 in those preserved in the deposit above the Peat 
^ (No. 5), though perhaps with more numerous ribs on the spores 
I from the Lacustrine clay (No. 2, &c.). This nucleus, according to 
Dr. Allen, has the character of C. fragilis Desv. Nos. 12 to 16 
and No. 17 (end view) are the principal varieties of this form, and 
are arranged in ascending order from left to right; Nos. 18 and 19 
! are somewhat irregular forms of the same species. 
Dr. Allen recognizes two other types of spores, one of which 
is broadly oval and with ribs less prominent than those of the 
C. fragilis form ; this occurs in No. 7c, &c., and has the characters 
; oiC. intermedia A. Br., a species now living in the lake. This form 
is figured in the last row on the wood cut. The other type of spore 
referred to above is figured beside it, and is smooth, long-oval and 
