WHIT£AVES.] DEVONIAN FOSSILS, MACKENZIE RIVER BASIN. 20!> 



Hay Eiver, forty miles above its mouth, R. G. McConnell, 1887 : one 

 specimen. 



At the suggestion of Mr. Wachsmuth, who has examined the speci- 

 men, this interesting littlo crinoid is here provisionally referred to 

 Meek's and Worthen's genus Arachnocrinus, though it appears to the 

 writer to differ therefrom in having two small and simple anal plates 

 and not one comparatively large one, which in Arachnocrinus is said 

 also to support "a lateral tube which is in line with the arm bases.'' 



VERMES. 



Spirorbis omphalodes, Goldfuss. 



Plate 28, fig.s. ?,, 4, 4a, 5 and ."la. 



Serpula omphalodes, Goldfuss. 1826-33. Petref. Germ., vol. 1, p. 225, pi. Ixvii, 



tig. 3. 

 S'jiirorbU omphalodes, Nicholson. 1874. Rep. Pal;eont, Prov. Ont., p. 121, fig. 54a. 



East bank of the Clearwater River, a few miles below the mouth of 

 the Pembina, Professoj' Macoun, 1875, and A. S. Cochrane, 1881 : five 

 or six specimens, adherent to Orthis striatula. Hay River, forty miles 

 above its mouth, R. G. McConnell, 1887, and Mackenzie River, at the 

 "Ramparts," R. G. McConnell, 1888: a few specimens which vary 

 considerably in shape at ditterent stages of growth, and which are 

 always attached to brachiopods or corals. 



In small specimens (such as the original of fig. 3) the outer volution 

 is rounded and somewhat depressed and the umbilicus usually, though 

 not always, comparatively wide. In large individuals (tig. 4) the outer 

 volution is elevated and subangular and the umbilicus narrow. The 

 surface is usually smooth or nearly so, but in some specimens (fig. 5) 

 which seem to be nearly intermediate between this species and the 

 next, the umbilical margin is seen to be distinctly j)licated, when ex- 

 amined under a lejis. 



Spirorbis Arkonensis, Nicholson. 



Spirorbis ArkonensiK, Nicholson. 1874. Rep. Paheont. Prov. Ont., p. 121, flgs. 

 54 b, c. 



Hay River, forty miles above its mouth, E. G. McConnell, 1887 : one 

 specimen attached to the dorsal valve of Spirifera cyrtinceformis. 



