SUPPLEMENT. 
507 
These buds or vesicles do not appear at every serrature, but only on 
every third or fourth, and are apparently opposite each other on the two 
sides of the rachis, but in reality alternating as do the serratures. Asso¬ 
ciated with these specimens, and apparently resulting from these vesicles, 
are numerous young graptolites. But although these young or embryonic 
forms of graptolites occur in such great numbers, it cannot yet be said 
that any specimens have been seen within the sac, or attached to the 
parent stipe*. 
The following figures will render more clear the preceding observations, and 
illustrate in some degree the forms described. 
12 3 
Fig. 1. A fragment of the stipe, showing the earlier development of these buds or vesicles. 
Fig. 2. A fragment where these buds are farther developed, and the upper ones less expanded 
than those below. 
Fig. 3. A longer stipe, preserving numerous expanded vesicles in a farther developed con¬ 
dition ; the most of them being broken, and some of them partially decomposed 
or absorbed, while they preserve very distinctly the delicate hair-like fibre before 
mentioned. 
* The first discovery of a specimen of this character is due to Mr. Whitfield, some three years since; 
and subsequently I have been indebted to Mr. J. B. Ellis, and to Mr. G. W. Taylor, for other specimens 
of the same, as well as for other forms; while I owe to Mr. Henry Canfield the possession of the very 
fine specimen of G. gracilis figured on page 512. The discovery of the young graptolites has been of later 
date, and they have recently been observed in large numbers. 
