1915] The Ottawa Naturalist. 61 



species. A second specimen seems to have only six rays, and 

 the normal number may prove to be seven. 



The holotype is No. 7789 in the Victoria Memorial Museum, 

 and is from the Crinoid beds (Hull formation) at the Kirkfield 

 Lift Lock, Ontario. 



LebETODISCUS INCONDITUS SP. NOV. 



(Plate 1, fig. 1). 



This is the form which is so common in the " Cystid bed" 

 below Parliament Hill and at Queen's Wharf, Ottawa, and which 

 has always been identified as Agelacrinites hillingsi. It differs 

 in several respects from that species. 



Description. 



Specimens circular in outline with a broad border of small 

 plates. Rays five in number, rather'stout, broad at the proximal 

 end and tapering rapidly. They are almost straight in small 

 specimens while in large ones they are slightly curved, four of 

 the rays having a contra-solar turn, and the fifth curved a little 

 in the opposite direction, so as to embrace the posterior inter- 

 radius. In some specimens, rays I, II, and III, are contra- 

 solar, and IV and V solar, while in the one selected as the holo- 

 type, IV is almost straight. The rays bear short interlocking 

 lateral covering plates, about twelve to fifteen pairs to a ray. 

 Median covering plates have not been seen. An appearance of 

 unusual width is given to the rays by the fact that the plates 

 of the inter-radii which abut against the rays are somewhat 

 higher than the remainder of the plates of the inter-radial spaces. 

 The supra-oral area is large, and covered by numerous 

 small plates. Their arrangement is difficult to make out, because 

 of the way the inter-ambulacral plates are mixed in with ray 

 and supra-oral series. In the center of the disc there appears to 

 be a central plate dove-taihng with two plates which are between 

 rays I and V, and abut on the posterior inter-radius. At the 

 sides and in front of the central plate are five more small plates, 

 one on each side and three in front of the central plate. Two 

 of the plates are inter-radial in position, one between rays II 

 and III, and one between III and IV. This is on the type. 

 On the small specimen next to it in the figure, there seem to be 

 only five plates which really belong to the supra-oral series, the 

 central, two posteriors, and two anterior laterals, between 

 rays II and III and III and V. 



The inter-radial areas are covered with small imbricating 

 plates, the plates of the inner part of the outer marginal band 

 being somewhat larger and wider than the plates between the 

 rays. The posterior inter-radius is wider than the others, and 



