SUPPLEMENT. 



S07 



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. 



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 firit discovery of a ipccimen of this character is due to Mr. Whitfieid, some three years since; 

 and subsequently I have been indebted to Mr. J. B. Ellis, and to Mr. G. W. Tatloe, for other gpeciraens 

 of the same, as well as for other forms; while I owe to Mr. IIenbt Canfield the possession of the very 

 fine s|K-cimen of G. gracilit figured on page 512. The discovery of the young graptolites has been of later 

 date, and they have recently been observed in largo numbers. 



