CANADIAN FOSSILS. 35 



The central pore of each division divides the angle into two equal 

 portions, and all the other pores upon the plate are parallel to this 

 central one ; consequently in each area they have three directions in 

 which they are at right angles to the sides of the triangular space in 

 which they are situated, but oblique with respect to the margins 

 of the plates. 



Explanation op Figures. Plate II. 



Figures 5a, 56. Posterior views of two specimens. 



" 5c. Anterior side of a specimen, enlarged to shew the azygos plates and 



poriferous areas. 

 " 5d. Ventral surface of 5a. 



Locality and formation. — Trenton limestone, City of Ottawa. 



Genus Dendroceinus, Hall. 



(Dendrocrikus, Hall, Paleontology of New York, volume ii., page 193.) 



Formula: 

 Basal plates, 5. 

 Sub-radials, 5. 

 Radials, 1X4+ 1X2 =6. 



Regular inter-radials, 0. 

 Azygos inter-radials, 1. 



Fig. 14. 

 Figure 14. Diagram of the structure of the cup in the genus Dendrocrinus. 



Generic characters. — In this genus there are five pentagonal basal 

 plates, and alternating above these a series of five sub-radials, one of 

 which has its superior angle truncated, and supports a large azygos 

 inter-radial. There are five rays alternating above the sub-radials ; 

 the ray on the left-hand side of the large azygos inter-radial has two 

 of its plates entering into the composition of the cup ; this ray is free, 

 from the third joint inclusive ; of the other four rays, only the first 

 joint is included in the cup. A large and long proboscis rises from 

 the azygos inter-radial plate. 



