re. 2 



ARISTOTLE'S LANTERN AND I'KHHJNATIIlr (ilKDI I 



ni 



-ait: . ,-v re.2 



I '.17 



236 



TEXT-FIGS. 231-236. Base of corona with attachment of lantern muscles in the Clypeastrina. 



231. Clypeasler subdepressus (Gray). West Indies. H. T. J. Coll., 887. X 2.8. Ambulacra! plates nearly roof OMT 

 the primordial interambulacral plates. Auricles are high, bearing the insertion of the protractor and two pain of retractor 

 muscles. 



232. The same. X 4.7. Showing the relation of primordial ambulacra! and intcrambularral platen, the latter shicl' ! 



233. Clypeaxter rosaccus (Linne). Bahamas. R.T.J. Coll., 888. X 5.7. The primordial intcrambulacral pl:r 

 less completely covered by the ambulacrals than in text -fig. 232. 



234. The same. Plates separated, inner view (p. 74). 



235. The same. Plates separated, viewed from peristomc. 



236. Echinarachnius panna (Lamarck). Eastport, Maine. X about 5.7. Auricles are transferred to the primordial 

 interambulacral plate and bear the insertion of protractor and one pair of retractor muscles. 



Lettering as in text-figs. 221-230, p. 193. 



