S4 DAWSON AND HINDE 



narssonia of Walcott, aud is uot distinguishable from Obolella pretiosa of Billings, from 

 the Quebec gioup of the Chatidière River and Cape Eouge, near Quebec. It is allied to O. 

 sagittalis, Salter, from the "Welsh Menevian, aud which also occurs in the zone of Para- 

 doxides Forchammeri in Sweden. This genus is thus, so far as known, characteristic of beds 

 older than the Levis ; but there is no reason why it might not occur thus far up in the 

 series. Shells of this species, usually pyritised, but sometimes black and flattened in 

 the plane of the shale, abound in the layers holding sponges. I figure (Fig. 27), from 

 drawings supplied by Prof. Hall, the structures of this little shell as they appear in some 

 of the best specimens.' 



Cystidean? — A small jointed stem, 1 cm. in length, with an elongated flattened mass 

 at one end, in which, however, no distinct plates can be seen. 



Trails of Annelids, elc. — On some surfaces are flattened and rounded grooves of differ- 

 ent sizes, but mostly small, and which may be trails of aquatic animals of different kinds. 

 They are not pyritous and present no trace of organic matter. Some of the larger are 

 spiral in the manner of Arenicolites spiralis, and these are pyritous. 



BUTHOTREPHIS PEKGRACILIS, Dawson. 



(Fig. 21.) 



Fig. 27. — Buihotrephis pergracilis. 



Stems very long aud flexuous, about 1 mm. in diameter, and obscurely striate longi- 

 tu.dinally ; sending off at their extremities short alternate or opposite branches. Allied to 

 B. gracilis, Hall, of the Siluro-Cambrian, but much more elongated aud slender. These 

 plants are replaced by pyrite and usually flattened, but the branches are occasionally 

 cylindrical, which seems to have been the original form. 



On some of the surfaces are groups of minute round pyritous spots, probably of organic 

 origin, aud perhaps ova or ovi-capsules of sponges or other animals, perhaps the vegeta- 

 tion or fructification of some aquatic plants. There are also a few oval or round, 

 perfectly flat or smooth, discs resembling flattened vesicles. On some of the slabs are 



' See appended Note. 



