SCHIZASTEE PHILIPPIT. 613 



quite twice as long as the posterior ones. The course of the petals much 

 as in S. fragilis; the posterior, however, slightly arching towards the median 

 posterior interambulacral line. Anterior groove shallower than in any other 

 species of the genus ; poriferous zones distinct ; but interporiferous space 

 quite narrow ; edges of groove very gradually rounded towards the sides, 

 not forming a sharp keel, due to the great depression of this part of the test, 

 as in the other species of the genus. Owing to the greater length of the 

 posterior petals, the posterior part of the peripetalous fasciole forms three 

 side.; of a rectangle ; the posterior side, somewhat concave, runs at a slight 

 angle with the anterior petal nearly to its extremity, crossing the point 

 of the petals at an obtuse angle ; the sides of the rectangle starting from 

 the point where the lateral fasciole, which runs nearly parallel with the 

 ambitus, branches off, and from the angle formed in the median anterior 

 interambulacral sjiace, which is somewhat nearer the apex than the extrem- 

 ity of the petal. The lateral fasciole curves towards the posterior extremity, 

 sloping gradually towards the ambitus, passing below the anal system at 

 the very edge of the test. The proportions of the anal system are nearly 

 those of S. fragilis ; the large plates which cover it are, however, more nu- 

 merous, and decrease quite gradually in size towards the anal opening ; 

 there are in S. fragilis only two or three rows of large plates surrounding a 

 number of comparatively much smaller ones, immediately round the anus. 

 The tuberculation of this species is comparatively coarser, and the tubercles 

 more distant than in its Arctic representative. The large tubercles on the 

 rounded edges of the anterior ambulacral groove are widely separated, when 

 compared to the close arrangement of the corresponding tubercles in S. 

 fragilis. The actinostome is much broader (transverse), compared to its 

 longitudinal diameter, than in S. fragilis. The general coloration of the two 

 species is similar, judging from dried and alcoholic specimens. The Antarc- 

 tic species is probably darker. 



