Superomarginals. — The number of superomarginals is shown 

 in the foregoing table. They are very flat and well rounded, so that 

 the external edge is wholly inconspicuous, except in those speci- 

 mens in which there is a series of short rounded spines along it. 

 In by far the larger number of the specimens which have come 

 under my observation, the superomarginals are covered with 

 rounded granules, which are larger near the inner edge of the 

 plate and gradually diminish in size outwards (PI. Ill, fig. 59). 



