MONOGRAPH OF THE EXISTING CEINOIDS. 241 



pinnulars or lean slightly distally, forming a wide meshed irregular and interrupted 

 reticulation. 



There are no spicules in the tentacles. 



Amphimetra spectabUis. There are no calcareous deposits in the perisome of 

 the pinnules. 



There appear to be no deposits in the tentacles. 



Amphimetra discoidea (fig. 791, p. 372). Each ambulacral lappet contains a 

 long but very narrow, very delicate plate, with unfinished borders, which lies at 

 right angles to the pinnulars. These are sometimes reduced to extremely narrow 

 plates, or even to straight roughened rods, just within the distal border of the 

 lappets. In the distal portion of the pinnules these may become broader and 

 more rounded. 



The perisome between the line of sacculi and the pinnulars contains a series of 

 irregular filmy longitudinally elongate plates of various sizes, sometimes quite 

 large and sometimes of only one or two meshes, which form an interrupted line just 

 beneath the line of sacculi ; sometimes these form a broad continuous double band, 

 and occasionally they are much reduced in size and widely scattered over the 

 perisome. 



The presence of spicules in the tentacles could not be determined. 



Amphimetra parilis. Each of the ambulacral lappets contains usually three 

 long very slender spicules, the two outer, running along the sides, slightly curved, 

 the distal much more than the proximal, and curving toward each other outwardly, 

 the other more irregular, and sometimes forked; in a lateral view of the pinnule 

 these appear as a rather closely set row of long spicules distally curved in opposite 

 directions, reaching downward nearly to the sacculi. Sometimes these spicules 

 may branch inwardly and these branches overlap, forming a narrow and long plate 

 within the lappet; in this case minute rounded plates alternating with them are 

 found between their bases over the spaces between the sacculi. 



The perisome over the genital glands is without calcareous deposits. 



The tentacles have a rather broad continuous layer of small spicules along the 

 distal side. 



Amphimetra papuensis. Each of the ambulacral lappets contains a single 

 straight roughened rod, which leans slightly distally. 



The perisome between the sacculi and the pinnulars contains at intervals deli- 

 cate filmy plates of from 6 to 15 meshes, which are usually more or less elongated 

 in the direction parallel to the edges of the pinnulars. 



There appear to be no deposits in the tentacles. 



Family STEPHANOMETRID^. 



Stephanometra monacantha. The perisome of the pinnules is without deposits. 

 There are no deposits in the tentacles. 



Stephanometra echinus. The perisome of the pinnules contains only extremely 

 minute scattered spicules. 



The tentacles contain inconspicuous proximal and distal lines of spicules. 



