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VOL. 81 



Schulze in essential characters, but differs from it in the character 

 of the gastral hexactins and of the discoctasters, the latter differing 

 in the same manner as those of R. unguiculatus just mentioned. 



Spiculation. — TJie principal parenchymalia are mainly slender 

 oxydiactins (fig. 16, c?), attaining a length of 6 mm and a thickness 

 of 8/1. to 20/>i at the middle. They usually form slender bundles, 



Figure IQ.—Rhaidocalyptus bidcntatus, new species: a, Gastral oxyhexactin, X 175+ ; 

 b, dermal tauractin, X 157+ ; c, dermal stauractln, X 175+ ; d, parenchymal diactin, 

 X 375 ; e, hexactinic form, X 375 ; /, oxyhexaster, X 375 ; g, hemihexactinic form, 

 X 375 ; h, discoctaster, X 375 



although they occasionally appear singly. The gradually tapering 

 rays are subterminally more or less rough. There are no points 

 worth special mention regarding the slenderer parenchymalia. 



The hypodermalia consist of large oxypentactins with paratropal 

 paratangentials, which are 5 mm to 6 mm in length and about 80/x 



