EEGADRELLA. 221 



To give the differential character of each species in the form 

 of a key : 



«. — Parietal ledge only indicated. With on5'cliaster (no oxyhexaster or oxystauraster). Large 

 oxypentactin parencliyiualia present along the superior rim of the lateral wall. Pricl^ly 

 parenchymal oxyhexactins not pres?nt. 

 a'. Witli true sieve-plate. CufF rudimentary. Without pro~tal needles in tufts on the 



lateral wall li. fliœnix O. ScHM. 



6'. Sieve-plate represented by a spicular wreath (corona) guarding the superior terminal 

 osculum. Cuft' well developed. With long prostal needles in tufts on the lateral 



wall R. komeyamai Ij. 



b — Parietal! ledge conspicuously developed. Without large oxypentactin parenchymalia along 

 the superior rim of the lateral wall. With oxyhexaster, predominantly in the form of 

 oxystauraster. Numerous small prickly oxyhexactins present in the parenchymalia. 

 (True sieve-plate present, surrounded by a well developed cuff. Without tufts of prostal 

 needles) R. okinoseana Ij. 



The idea of removing E. okinoseana altogether from the 

 genus has often suggested itself to my mind. In fact I think 

 this step might be taken with some practical advantage to the 

 systematic. The presence of oxyhexasters and oxystaurasters 

 instead of onychasters, and also of small, prickly or spinose, 

 parenchymal oxyhexactins in large numbers, keep this species 

 somewhat apart from the other two, which iîiter se show an 

 essential agreement in spiculation. Another not unimportant dis- 

 tinction from those species seems to lie in the fact that in it 

 the large oxypentactin parenchymalia, which in E. phœnix give 

 a strong support to the sieve-plate and in B. homey amal supply 

 the coronal rays, are wanting. Perhaps it may not be altogether 

 inappropriate to associate R. okinoseana generically with Corbitella 

 sjyeciosa { = Habrodidyum speciosum Q[]0Y & G KiM.k^J)), whicb, to 

 judge from W. Thomson's ('68) statements, seems to agree in a 

 measure with that species, amongst other points in being in 

 possession of oxyhexasters and evidently also of small smooth- 

 rayed hexactins which may correspond to the spinose parenchy- 

 mal oxyhexactin of R. okinoseana. Howver, in view of uncertain- 



