321 



or flooring-plates) appear almost anchylosed, but the pores between them 

 are very clear, and one can trace the original median line of Suture ; the 

 ambulacrals or covering-plates were stout, at least in the proximal 



— dmb 



Fig. 23. Fig. 24. 



Sfer/anohlastus otfawacnsis, slightly restored from the type-specimens, and 

 X 3 diam. 23, oral surface ; 24, from 1. post, radius, adanib. adambulacrals 

 or side-plates; amh, ambulacrals or covering plates, mostly removed ; As 

 anus surrounded by small plates ; B, basal ; I R, large median inter- 

 radial ; O, f> orals or proximal ambulaoraLs ; p, pores between side 

 plates ; R. radial ; St, fragment of stem. 



regions, where they seem to have combined with the spear-head plates to 

 form a solid roof over mouth and food-grooves. Stem small, round, -vfith 

 lumen less than half the diameter. Fifty years ago Steganohlastus would 

 have been described as a generalized or synthetic type, with Cystid, Blas- 

 toid, Crinoid and Asteroid affinities ; it is simpler to regard it as a specia- 

 lized Edrioasteroid, in which features common in stalked genera of other 

 classes have been evolved independently under similar conditions of exis- 

 tence." 



Mathbria beevis, Whiteaves. 



Mathcria brevis, Whiteaves May, 1903. Ottawa Naturalist, vol. XVII, p. 33, 



figs. 1 and 1 a ; and Geol . Mag. for A ug. , 1903, 

 N. S., Dec. IV, vol. X, p. 358, figs. 1 and 1 a. 



"The genus Matheria was described by E. Billings in 1858, in the 

 third volume of the Canadian Naturalist and Geologist. It was based 

 upon a single species, the M. tener of Billings, a small lamellibranchiate 

 or pelecypodous bivalve, from the Trenton limestone of Lake St. John, 

 P.Q. Matlieria appears to be most nearly related to Cyrtodonta and 



