from the Quebec Group of Point LSvis. 141 



narily in their dimensions, examples apparently belonging 

 to this species ranging from about one line in length to more 

 than a quarter of an inch. It is probable therefore that, 

 in spite of theidentity of shape, more than one form is included 

 under this head. The species to which D. acuminata is most 

 nearly allied is D. campamdata^ from which it is distinguished 

 by the fact that the mucro is not sharply separated from the 

 body of the capsule, whilst its figure is quite different. 



Dawsonia rotundaj Nich. 



Capsule minute, oval or circular in outline, consisting of a 

 flattened marginal limb surrounding a central elevated seed- 

 like body (the cast of the interior of the capsule) . The mar- 

 ginal limb is quite smooth and exhibits no structure ; but the 

 central rounded mass often exhibits stride or furrows, which are 

 disposed concentrically round a marginal point (fig. 3, b, b') . 

 Dimensions very ccyistant, the circular specimens having a 

 diameter of a line or a little less, whilst the oval specimens 

 have a long diameter of about a line by a short diameter of 

 about one twentieth of an inch. 



This exceedingly distinct form cannot be confounded with 

 any of the ordinary forms of Dawsonia. It is found very 

 abundantly in certain beds of the Point-L^vis shales. It is 

 curious to note how closely D. rotunda approximates in struc- 

 ture to the " statoblasts " of the Polyzoa, since the capsule, 

 according to all appearances, has been composed of two concavo- 

 convex disks united by their faces, the union being effected by 

 the adhesion of a broad marginal belt on each disk. I have 

 not as yet determined this species from any of the Graptoliti- 

 ferous strata of Britain. 



Daivsonia tenuistriata, Nich. 



Capsule oval, obtusely ovate, satchel-shaped, or nearlyround, 

 covered with fine concentric striae, which surround a prominent 

 elevated point. This point (the mucro) marginal, submarginab 

 subcentral, or central. The strise differing in closeness and 

 fineness, but always delicate and regular in their arrangement. 

 Dimensions, like the shape, very variable, but the length usually 

 varying from one tenth to one fifth of an inch. (Fig. 3, c, c', 

 d, d'.) 



The forms included under this head are extremely like small 

 Brachiopods of the genera Lingula^ Obolella^ and Discina ; and 

 it is difficult to convince one's self that they do not truly belong 

 to this group. That they are not Brachiopods, however, 

 appears certain from the following considerations. They occur 

 in great plenty, along with the two previously described forms 



