170 s. GOTf); 



Specim. F 4. 3. 2.-2. 3. 4., 3. 2.-2. 3. 4., 4. 3. 2.-2. 3. 4., 

 3. 2.-2. 3., 3. 2.-2. 3. 4. 6. 



Theso formula) represent fairly well the modal condition of 

 the snperomarginal spines of this species ; but in a few extreme 

 cases the number of unarmed spines next the first snperomarginal 

 may amount to as many as five or six. Again in specim. F of 

 the examples above cited the fourth superomai-ginal on the last 

 side of the last interradius had an exceedingly small spine barely 

 distinguishable from the neighbouring granules. 



In the basal portion of the arms, there is generally a small 

 naked zone on the inner side of the abactinal surface of the 

 suj^eromarginals (PL III, fig. 47). The proximal and distal faces 

 of the fasciolar grooves are covered with capillary spinelets, and 

 the remaining portions are covered with granules, which are large 

 and conical immediately on the outer side of the large spine and 

 gradually become slender and cylindrical towards the margins and 

 finally pass over into the capillary spinelets of the fasciolar 



grooves. 



The superomarginals are higher than broad, and stand up 

 erect, i.e. their external surfaces are nearly perpendicular. The 

 abactinal surface is at right angles to the margin at the base of the 

 arms, but becomes inclined more distally, the inclination sometimes 

 amounting to about 30° at the middle of the arm. 



Inferomarginals. — The inferomarginals are very much broader 

 than long, and make an angle of about 30- with the ambulacral 

 furrow (PL III, fig. 44, 4G). The general armature may bo des- 

 cribed as coarse and spiny. The spinelets along the margins are 

 subcapillary, but they form a less regular row than in Astrop. 

 scoparius and are less fine. An irregular row of 4-0 large. 



