26 The Ottawa Naturalist. [May 



the outer border of the arms. In the new plates, near the ends 

 of the arms, thickening in this direction is at first rapid. A 

 straight line connecting the outer border of the fifth and seventh 

 marginals makes an angle of sixteen degrees with the axis of 

 the ray. The rate of widening is not so rapid during the later 

 period of growth and a line connecting the outer borders of the 

 second and fourth arm marginals makes an angle of only eight 

 degrees with the axis. Function has demanded a greater growth 

 of the first arm marginal and particularly of the side next the 

 interradial marginal. The face against the latter is 1.3 mm. 

 loner while its distal face measures but 0.8 mm. This increase 



o 



of growth near the disc has thrown the marginal line rapidly 

 outward and it swings across the distal end of the interradial 

 marginal in a broad, hyperbolic curve. The outer edges of each 

 arm thus present a very gentle sigmoid "line of beaut}'." The 

 extension of the arm is nearly equal to the diameter of the disc. 

 Disc radius about 4.4 mm., arm terminal 11.6 mm. from disc 

 centre. The species can be easily determined from its marginals 

 alone. More detailed descriptions of the other ossicles will be 

 given later. 



The specimen was collected by Mr. J. E. Narraway from the 

 lower part of the Black River limestone on the top of a small 

 hill a few rods west of the City View Post Office and is how in 

 his private collection. It was lying in its bed with oral face 

 uppermost. I have named the specimen after Mr. Narraway 

 in slight appreciation of the debt due him for the discovery of 

 such a remarkable type. 



In a following portion of this paper I shall deal specifically 

 with habit and adaptation as revealed by the skeletal elements 

 preserved. 



VARIATION IN PLANT LIFE, ITS BIOLOGICAL SIG- 

 NIFICANCE AND PRACTICAL VALUE.* 



All evolution, be it evolution of humanity from a lower to 

 a higher level, or the evolution of the animal or vegetable king- 

 dom from primary types to more perfect ones, is based upon 

 two principles, the principle of heredity and the principle of 

 variation. 



*Synopsis of lecture delivered before the Ottawa Field-Naturalists' 

 Club, February 13th, 1912, by Dr. M. O. Malte, Dominion Seed Branch. 

 Ottawa. 



