SPATANGUS PURPUREUS. 565 



Rashi scarcely more than one and a quarter times broader than long, and not 

 exceeding in width the widest part of the actinal plastron. The actinostome 

 is more distant from the anterior edge than in the two European species ; the 

 general £>roportions of the tuberculation and size of the spines much as in S. 

 purpureus on the actinal side. The small tubercles covering the abactinal sur- 

 face are much larger and more closely crowded than in the other species, 

 covering the whole abactinal part of the test, including the anterior groove, 

 with a very uniform granulation, carrying minute, slender, curved spines. 

 In the apical portion of the anterior lateral interambulacra there are a few 

 irregularly arranged primary tubercles carrying larger spines ; on the outer 

 slopes of the anterior groove, adjoining the ambulacral zones, irregular ver- 

 tical lines of large primary tubercles, carrying large spines, are found ex- 

 tending from the apical system to the ambitus. The lateral petals are 

 moderately broad, petaloid, proportionally shorter than in the other species. 

 The color in alcohol is dark violet. 



Spatangus purpureus 



! V Spatagus purpureus Mull.. 177G, Prod. 2850. 

 Spatangus purpureus Leske, 1778, Kl. Add., p. 170. 



PL XF. f. 10-22; PL XI V a . /. 1 ; PL XIX. f. 5-6; PL XXVI. f. 24-27; 

 PL XXXII. f. 17, is; PL XXXIV. f. 3, 4; PL XXXVII f. m ; PL 

 XXXVIII f. 34, 35. 



The outline of the test of this species, seen from above, is pretty uniform ; 

 it is broadly heart-shaped, slightly angular, truncated at the posterior ex- 

 tremity. Anterior groove deepest near the ambitus ; apical system slightly 

 anterior ; vertex posterior ; geometrical pole about half-way between the two. 

 The height is very variable. Posterior ambulacral petals petaloid, closed ; 

 interporiferous space broad ; interporiferous zone more convex than the inner 

 one. Anterior lateral petals longer than the posterior ones ; odd anterior 

 poriferous zone reduced to distant diverging rows of pairs of pores, the 

 interporiferous space attaining its greatest breadth somewhat above the am- 

 bitus. Pores of lateral ambulacra large, connected by a deep furrow. The 

 plates of the abactinal part of the interambulacral spaces carry large per- 

 forated crenulate tubercles of very variable size, most numerous adjoining 

 the median line, and extending in a V-shaped ime or forming a triangular 



