470 MICROCYPHUS ZIGZAG. 



These larger specimens differ from the smaller ones in the greater concen- 

 tration of the tubercles on the plates of both areas; the median and hori- 

 zontal sutures are well-defined bare furrows, sloping gradually towards the 

 tubercles. The larger tubercles form an irregular horizontal row about 

 the middle of each plate; the principal vertical row is no longer quite cen- 

 tral, but somewhat nearer the poriferous zone. The bare median spaces 

 extend fully as far along the test, nearly reaching the actinostome, to within 

 a couple of coronal plates from it. The abactinal system shows no special 

 change, the tubercles near the anal edge being only comparatively larger and 

 more prominent. The actinostome is nearly circular. The poriferous zone, 

 as well as the tuberculiferous parts of the test, are of a greenish-yellow tint, 

 the latter standing out prominently above the dark chocolate-colored bare 

 median spaces. 



This species is interesting as forming a link between Microcyphus and 

 Amblypneustes. It has the structural features of the former and the facies 

 of the latter. All the large specimens I have seen are unfortunately de- 

 nuded and have no actinal membrane. 



This may possibly be the Cidaris bothryoides of Klein ; his figure has a 

 distant resemblance to the large specimen figured on PI. VIII'. f. ll, 12 of this 

 Revision, and it was probably also specimens of this size to which Professor 

 Agassi/, alludes, as existing in Stokes's Collection in the Anatomic du Genre 

 Echinus under the name of Pleurechinus bothryoides, a totally different 

 thing from what he labelled as such in Michelin's Collection. The charac- 

 teristic notice of the coronal plates as transverse costae would seem to leave 

 but little doubt on that subject. 



Japan ; Tasmania ; Philippine Islands. 



