from the Quebec Group of Point Levis. 139 



Dawsonia, Nich. 



I propose this genus, named in honour of Principal Dawson 

 of Montreal, for the singular bodies which I have elsewhere 

 (Monograph Brit. Grapt. part i, p. 71, fig. 41) described as the 

 "ovarian vesicles " of Graptolites. I am led to this step by 

 the extreme inconvenience of applying a general name like 

 " ovarian capsules " to fossils which often present differences 

 of specific value, which cannot be properly described unless a 

 special name be adopted. Moreover good authorities are dis- 

 posed to doubt whether these bodies are truly to be compared 

 to the "ovarian capsules " of the Graptolites ; and the name of 

 " grapto-gonophores," which I originally applied to them 

 (Geological Magazine, vol. iii. p. 448), is open to other grave 

 objections as well. Upon the whole, therefore, it appears to 

 me best to found for these fossils the provisional genus Daw- 

 sonia, which implies no theory as to their nature, and which 

 will enable us to specify and name such varieties as appear to 

 be distinct. In fact this course seems to me to be the best, 

 even whilst I retain my belief as to their truly being the 

 " ovarian capsules " of Graptolites ; for it cannot be hoped 

 that we shall ever be able to refer each (or perhaps any) par- 

 ticular species of Dawsonia to the species of Graptolite by which 

 it was produced. 



The characters of the genus are as follows : — Horny or chi- 

 tinous capsules of a rounded, oval, conical, or campanulate 

 shape, furnished in most cases with a little spine or mucro, and 

 having a marginal filament exactly resembling the solid axis 

 of a Graptolite. The marginal fibre sometimes complete, 

 sometimes ruptm-ed opposite to the mucro. The mucro some- 

 times apparently wanting, sometimes marginal, submarginal, 

 subcentral, or central. The surface smooth or concentrically 

 striated. 



I first discovered the bodies included under this head in the 

 Lower Silurian anthracitic shales of the south of Scotland, 

 where they occur in great numbers along with the Graptolites ; 

 and, as before remarked, I regarded them as bearing to the 

 Graptolites the same relation tliat the "ovarian capsules" do 

 to the colonies of the Sertularians. Subsequently I detected 

 similar bodies in the Graptolitic mudstones of the Coniston 

 series of the north of England, also associated with numerous 

 Graptolites. I consider it the very strongest confirmation of 

 my views as to the nature of these fossils that I have now dis- 

 covered them in vast numbers in the Quebec group, associated 

 with the Graptolites of that formation. Not only are they 

 very numerous, but there are at least three distinct forms of 



