54 [Assembly 



Phyllogkaptus ttpus in two extreme forms. 

 A', 



A', Y. 



1 1. 



— I- 



■"^ 



Under this genus are described : 

 Phyllogra'ptus typus, P. ilicifolius, P. angustifolius, and P. similis. 



While these discoveries have been made in Canada, giving us for 

 the first time a correct knowledge of the mode of growth and the 

 varying forms of these bodies, I have not neglected opportunities of 

 increasing our knowledge of these fossils from localities within my 

 reach. The locality of graptolites near Albany has heretofore fur- 

 nished several species, which, now that we know better their original 

 forms, offer additional information, and become of greater interest 

 both in their zoological and geological relations. 



At this locality, some specimens have been obtained which show 

 apparently the mode of reproduction in this family of animals, which 

 is more similar to the hydroid polyps than to the Bryozoa*. 



The specimens in which this fieature has been observed, first show 

 a slight swelling or vesicle proceeding from the axils of the serra- 

 tures : this vesicle, which in the beginning is barely perceptible 

 beyond the outlines of the margin, swells and becomes elongated, 

 the extremity finally much inflated, and the base of the footstalk 

 extended and attenuate. As this process of development goes on, 

 the sac or inflated portion curves downwards, and finally becomes 

 ruptured or dehiscent on the lower side near the extremity. At this 

 period, and sometimes previously, the sac, which appears to be an 

 extremely thin membrane and almost without substance, shows one 

 or two elongated fibres, like the central midrib or the marginal 

 longitudinal fibre of the graptolites. At a more advanced stage the 



* This notice was read at the meeting of the American Association for the Advance- 

 ment of Science at Baltimore in 1858, accompanied also by references to the Canadian 

 graptolites. 



