250 VERRILL 



The interradial spaces, beneath, are very small and narrow, with 

 very few ossicles, each of which bears a group of three or four 

 slender, elongated spinules. These spaces are very much smaller 

 than in S. stimpsoni, and still smaller as compared with S. endeca. 

 The adambulacral plates bear a longitudinal group of three, or 

 sometimes four, long, slender, furrow-spines, and outside of these a 

 transverse group of four or five rather larger and longer ones. The 

 oral plates bear six long, slender blunt preoral spines, the two middle 

 ones longest, and four or five small lateral ones on each side. 



The adambulacral spines, especially the furrow-series, are much 

 longer than in 5". stimpsoni and 5". endeca, both of those usually 

 having but two small and short furrow-spines on each plate in speci- 

 mens of similar size. 



This type was from Virago Sound, British Columbia, in 8 to 15 

 fathoms (G. M. Dawson, Canadian Geological Survey). It was 

 dried and not in a good state of preservation. Much larger and 

 better specimens have subsequently been obtained, many of which 

 have been sent to me by the Canadian Geological Survey. 



One of the larger dry specimens from Powell Island, Straits of 

 Georgia, has the radii 34 mm. and 100 mm. ; ratio, about i : 3. (PI. 

 xci, fig. 2; xcii, fig. I.) 



Rays thirteen, rather long and narrow, tapering gradually, the 

 disk being smaller and the rays rather longer than is usual in 

 S. endeca. 



The dorsal pseudopaxillas, many of which are preserved expanded, 

 are small, crowded, regularly stellate, with a truncate or infundibuli- 

 form top, surrounded by about twelve to eighteen small, slender 

 spinules, webbed together, and mostly with one to three very small 

 central spines, though many have more. 



The plates are small, partly four-lobed and partly three-lobed, 

 with a prominent central mammilla. They are everywhere closely 

 imbricated, mostly arranged in quincunx order, and on the sides of 

 the rays they stand in close and pretty regularly alternating oblique 

 rows. 



The papulse are numerous and small; they stand partly in small 

 groups and partly singly. 



The madreporic plate is large and prominent, with numerous fine 

 gyri, and with three or four pseudopaxillse on its surface, near the 

 margin. 



The inferomarginal plates are large and very prominent, trans- 

 versely oblong, with thirty to forty or more very slender spinules 



