50 THE CANADIAN NATURALIST. [Feb. 



with the Hydroidea, and would indicate the sertularians as their 

 nearest analogues.* 



Upon the surfaces of the slate where these bodies occur, there 

 are numerous graptolitic germs, or young graptolites of extremely 

 minute proportions, ranging from those where the first indications 

 of their form can be discovered, through successive stages of 

 development till they have assumed the determinate characters of 

 the species. 



In several examples, these minute germs have been detected 

 near to and in contact with the reproductive sac ; and in one case, 

 there is but a hair's-breadth between one of the fibres of the sac 

 and one of the oblique processes at the base of the germ. It can- 

 not be said that we have detected the germ actually within the 

 sac ; but the numerous young individuals lying near them, and 

 upon the surfaces of the same laminae, offer very good arguments 

 for supposing that they have been thus derived. 



The earliest defined form which we observe in the young grap- 

 tolites consists of the initial point or radicle; a diverging process 

 of similar character on each side, but not quite opposite ; a longi- 

 tudinal axis of greater or less extent ; and a sac-like covering, or 

 thin pellicle of graptolitic test, which has scarcely assumed the 

 form of cellules, but which is most extended in the direction of 

 the common body along the solid axis. This little sac contains 

 the germ of the zoophyte, which, extending itself as the common 

 body in its canal along the axis, gives origin to the budding 

 which develops the successive cellules and the gradual building up 

 of the stipe. **^* *.***'* 



The numerous individuals of entire or nearly entire fronds 

 illustrated in this memoir, as well as large numbers of others 

 examined, serve to give a pretty clear idea of the general form of 



* In the recent Sertularia and Campanularia we find ovarian vesicles, 

 in which a number of ovules may be enclosed in a common envelope. 

 These vesicles are developed along the side of a stipe or branch, and 

 the ovules are often arranged along a central axis, each one communi- 

 cating with the common axis of the zoophyte. [Jas. J. Lister, Philo- 

 sophical Transactions, 1834, pp. 365-388, pi. ix. Cited also by Dana, 

 " Structure and Classification of Zoophytes.' 1 ] 



Prof. McCoy has stated (British Palaozoic Fossils, p. 4) that he has 

 found near the base of the cellules of graptolites, a transverse partition 

 or diaphragm, similar to what may be observed in some sertularians 

 and which he regards as proving similar relations ; but I have not dis- 

 covered in any American specimens evidence of such cell-diaphragms. 



