1865.] GRAPTOLITES OF THE QUEBEC GROUP. 49 



distorted by pressure, a longitudinal section of the stipe in the 

 direction of its greatest diameter shows the cellules scarcely nar- 

 rowed at their origin with the common body ; while in a lateral 

 view of the specimen, the base of the cellule is seen to be much 

 wider than the orifice. 



In many of the species a transverse section of the cellule near 

 the base is quadrangular, becoming more rounded towards the 

 aperture; and when the upper part of the cellule is free, the aper- 

 ture is round or elliptical, and in some specimens the calycle is 

 elliptical or cylindrical throughout its entire length. We have 

 examples of the quadrangular cellules in G. extensus and G. octo- 

 brachiatus, as well as in two species of Phyllograptus. Where the 

 cellules are more nearly isolated, they approach more and more to 

 the cylindrical form. As examples of cellules contracted towards 

 the aperture, we have Graptolithus priodon, Barrande, and G. 

 CUntonensts, Hall. * * * * * * * 



In 1858, I laid before the American Association for the 

 Advancement of Science a notice, with some illustrations of grap- 

 tolite stipes, bearing what I then regarded, and do still regard, as 

 the reproductive cells or ovarian vesicles. These cells first appear 

 as small ovate buds upon the margins, projecting but little beyond 

 the regular cellules, and, becoming enlarged, form elongated sacs 

 with swollen extremities, which are finally dehiscent ; and then, 

 as I suppose, discharging the ovules or germs, are gradually 

 absorbed or dissipated. 



Although these sacs are distinctly defined, they have scarcely 

 any apparent substance, except along the lateral margins, which 

 are limited by a filiform extension resembling the solid axis of a 

 graptolite. There are likewise numerous fibres of this kind 

 traversing the sacs ; and these sometimes remain attached to the 

 original stipe after the other parts are separated. In one example 

 we have conclusive evidence that they are connected with the solid 

 axis of the parent stipe. 



In one specimen the ordinary cellules are removed, and the 

 fibres are still seen joined to the axis, showing the origin of the 

 reproductive sacs. In most specimens bearing these sacs, the cel- 

 lules of the stipe are so obscure that the species cannot be deter- 

 mined ; but in one case we find them attached to a well-marked 

 type of G. Whitfieldl. 



This mode of reproduction in the graptolites shows much analogy 

 Vol. II d No. 1. 



