SALMACIS RARISPINA. 475 



plates carrying tubercles, and diminishing rapidly towards the anus. The 

 auricles of this species are remarkably broad, thin, with a high connecting 

 ridge. 



Salmacis rarispina 



'.Salmacis rarispiaus Agass., 1846, C. R. Ann. Sc. Nat., VI. 



PI. VHP. f. 4-6. 



Test usually quite conical, much thinner than in other species of Salmacis. 

 The coronal plates are comparatively higher. The abactinal system large, 

 with a broad genital ring and genital plates of equal size. Ocular plates 

 large, pentagonal, completely excluded from the large anal system ; this is 

 covered by large plates decreasing rapidly in size towards the anus, carrying, 

 as well as the anal edge of the genital plates, small secondaries. In the inter- 

 ambulacral space above the ambitus the primary tubercles are small, nearly 

 of uniform size, far apart, forming only two continuous vertical rows next 

 to the poriferous zone. The other tubercles are more irregularly arranged, 

 forming disconnected vertical rows, and leaving the greater part of the me- 

 dian interambulacral space bare. The coronal plates above the ambitus are 

 comparatively bare, owing to the distance of the primary tubercles, and the 

 small size and small number of the miliaries which are extremely distant. 

 The test above the ambitus is a grayish color, with lozenge-shaped figures 

 along the horizontal sutures similar to the pattern so frequently found among 

 species of Echinus. In the ambulacral space the arrangement of the pri- 

 mary tubercles and the pattern of coloration are similar to that of the inter- 

 ambulacral ; there are two outer regular vertical rows and two inner irregular 

 disconnected rows of primaries. On the actinal side the tubercles are large, 

 quite closely packed, gradually diminishing in size towards the actinostome, 

 which is small and quite sunken, almost circular. The spines are long, 

 slender, pointed, somewhat flattened, straw-colored, with from seven to eight 

 brilliant purplish transverse bands. Sutural pores quite minute. 



