142 On some Fossils from the Quebec Group. 



of Daivsonia, in the shales of the Quebec group at Point Levis. 

 They have exactly the same texture, and are in just the same 

 state of mineralization as the ordinary forms of Daiosonia. 

 Their shape is so variable that we should have to believe that 

 there were at least fom* or five distinct species of small Brachi- 

 opods in these beds, which is very unlikely. Lastly, the 

 position of the elevated point, which would constitute the beak 

 if they were Brachiopods, is exceedingly variable, being most 

 commonly placed a little within the margin, but being at other 

 times subcentral or marginal. On the other hand all the re- 

 quirements of the case are met by the supposition that we have 

 in these singular fossils the homy capsules of a species of 

 Dawsonia^ in which the capsule was furnished with stiiee con- 

 centric to the mucro. On this view the elevated point round 

 which the stride are disposed is the mucro ; and its variable 

 position, as well as the variable shape of the capsule, can be 

 readily explained by supposing that it is due to the variable 

 direction in which the capsule has been compressed. When 

 compressed laterally the mucro will be marginal ; when com- 

 pressed from above downwards the mucro will be more or less 

 nearly central ; when compressed obliquely the mucro will be 

 submarginal. 



Daicsonia campanulata^ Nich. 



Capsule bell-shaped, with a very distinct marginal fibre and 

 a strong and distinct mucro. The mucro does not pass insen- 

 sibly into the body of the capsule, but is sharply separated from 

 it. The surface of the capsule smooth. The marginal fibre 

 sometimes continuous, sometimes ruptured opposite to the 

 mucro (fig. 3, e,/). Dimensions extremely variable ; average 

 specimens about one fifth of an inch in length by three twen- 

 tieths of an inch in breadth. 



Ordinary specimens of this form present the appearance 

 shown in fig. 3, e, where the capsule has been compressed 

 laterally and the mucro is marginal. Many specimens, how- 

 ever, present the appearance shown in fig. 3,/, in which the 

 compression has been directed from above downwards, and the 

 mucro forms an elevated point within the margin, sm-rounded 

 by a few concentric ridges. This appearance might lead to its 

 being confounded with Dawsonia tenuistriata ; but it is really 

 very different. In the latter the concentric stride which surround 

 the mucro are really proper to the capsule, and they are extremely 

 fine, delicate, and regular ; in vertically compressed specimens 

 of D. camimmdata^ on the other hand, the concentric ridges 

 which surround the mucro are truly foreign to the capsule, 

 being merely the result of the direction of the pressure, and 



