48 ECHITSrODERMA OF THE TNDIAK MtTSETTM, PART VIT. 



long, conical, the cirrus sockets in two or three columns in each radial area, 

 well separated, each with a raised horse-shoe-shaped rim which surrounds it 

 proximally and laterally ; no pinnules on the first 10 or 12 brachials. 



(M) ATELECRINID/E, p. 251. 



(Cf. key 22.) 



b* no basals : cirrus sockets without a raised rim ; pinnules from the second, or 

 at furthest the fourth, brachial, onward, 

 c' oral pinnules long and slender, composed of very numerous short seg- 

 ments and bearing a terminal comb ; mouth usually marginal to sub- 

 central ; anal tube usually central. 



(O) COMASTERID^, p. 6S. 



(Cf. keys 5, 7, 8.) 



c* oral pinnules smooth distally, without a comb ; mouth always central, or 

 nearly so ; anal tube lateral. 



d' elements of the IBr series united liy ])fteudo-syzygy, not differing exter- 

 nally from a true syzygy. 



(0) ZYOOMETRID.?:, p. 99. 



{Cf. keys 5, 9.) 



d'' elements of the IBr series united by synarthry. 



e' all the pinnules sharply triangular or prismatic, rather stout, the outer 

 with comparatively short segments which do not have swollen articula- 

 tions, their ambulacra bordered with well-developed side and covering 

 plates. 



f P, very delicate, sliort, flexible, and weak, the first two segments 

 greatly enlarged, the remainder very small and squarish ; P.; much 

 enlarged and stiffened, with elongated segments : elements of the 

 division series thin dorsoventrally and well separated , but sometimes 

 with more or less irregular ventrolateral processes ; disk globose, 

 compact, entirely enclosed by a solid pavement of plates ; muscular 

 fossc-p on the articular faces of the radials transversely linear. 



(0) C.4L0METRID/E, p. 177. 



{Cf. keys 5, 16.) 



f^ I', longer than P, , or, if shorter, of the same character; P, resem- 

 bling the succeeding pinnules ; elements of the division series very 

 deep dorsoventrally and sharply flattened laterally against their 

 neighbours, witliout ventrolateral processes; ventral surface of disk 

 usually slightly concave, the sides not visible; disk studded with 

 roimded calcareous plates whicli very rarely form a compact 

 pavement ; muscular fossae on the articular faces of the radials very 

 high, much higher than broad, and narrow. 



