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A NEW GENUS AND THREE NEW SPECIES OF CRINOTDS 

 FROM THE TRENTON FORMATION WITH NOTES ON 

 - A LARGE SPECIMEN OF DENDROCRINUS PRO- 

 BOSCIDIATUS. 



Walter R. Billixgs. 



(Read, 3rd March, 1887). 



OTTAAVACRINUS, n. cjen. 

 Cup, obconical. 



Underbasals five ; pentagonal. 



Basals five ; one pentagonal, two hexagonal and two hept 



Radials five; four simple and one the right posterior compound. 

 In the type species three are pentagonal, one tetragonal and tlie com- 

 pound made up of a heptagonal followed by a pentagonal plate. 



Arms five ; composed of tetragonal pieces. No pinnules. 



Anal plate heptagonal resting on the posterior basal and the lower 

 plate of the right posterior radial as in Dendrocrinus and supporting 

 a ventral tube which, so far as seen, is composed of horizontal rows of 

 hexagonal pieces which alternate with those in the adjoining rows. 



This genus is most nearly related to Dendrocrinus, from which it 

 jnincipally differs in tlie shape and size of the right posterior basal ; 

 the shape of the posterior basal, the right anterior basal and the 

 posterior radial ; and in the arrangement of the plates of the ventral 

 sac, which are in vertical rows in the latter genus. 



Although the type specimen of this genus was discovered at Hull, 

 Ottawa County, P.Q., I felt justified in naming it as above owing to 

 to the fact that, when referring to the Trenton Formation of this 

 district, naturalists use the general term Ottawa Canada. 



OTTAWACRINUS TYPUS n. Sp. 



Cup, slender, obconical, 0^2 inch in height, tapeiing from 0.12 

 inch at base to 0.17 inch at base of arms. Surface of plates smooth. 



Underbasals five ; pentagonal, sub-equal. 



Basals five ; the posterior, left posterior, right anterior and left 

 anterior are large the largest plates in the cuj) and the right 



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