222 I. IJIMA : HEXACTINELLIDA. I. 



ties in our knowledge of Corhitella, R. ohinoseana may after all 

 for the present best be left as it is. 



Regadvella is evidently mucli more nearly related to Tccgeria 

 F. E. ScH. than may appear at first sight. The coronal wreath 

 of T. jndchra, the only known species of that genus, is to be 

 considered as of only specific rather than generic value, as will 

 be enunciated anon under R. komeyamai which possesses the 

 same structure. The spiculation in the two genera is to a far- 

 reaching extent, essentially similar. The small, spinose, paren- 

 chymal oxyhexactin of R. ohinoseana is represented in T. pulchra 

 Chall.-Eep., pi. xr, fig. 2). All the three kinds of hexasters 

 seen in both R. phœnix and R. Icomeyamal are here likewise 

 present. Floricomes and graphioconies were mentioned as such 

 by F. E. Schulze (/. c, p. 95) in T. pulchra ; for onychasters I 

 take the hexaster-form which that writer has specially described 

 as having 4-6 small hooks j^i'ojectiny transversely at the extremity 

 of rather slender terminals. Now, what constitutes the most 

 characteristic feature of T. pulchra is the presence, in addition 

 to above-mentioned hexaster-forms, of well-developed discohexas- 

 ters, whose arched terminal disc bears six strong hooks. The 

 spicule called by F. E. Schulze the * discohexact ' (/. c, pi. xr, 

 fig. 3) is, in my opinion, to be classed under the above dis- 

 cohexaster simply as a case of hexactiuose discohexaster.'" Since 

 now such a discohexaster differs from an onychaster merely in 

 the more strongly developed state of the terminal disc or whorl 

 of teeth, the distinction of Tœgcria from Regadrella may be said 

 to rest on nothing more than the relative degree of the develop- 

 ment of parts in certain discohexasters. 



*Tlie hexactiuose discohexaster apparently occurs also n\ Eudidyum elcgans desciùbed by 

 ]\Iaksiiall ('75)- With a better knowledge, than we at present have of this species, it may 

 possibly be found necessary to icgard Tcc(/aia F. E. Hvn. as only a synonym of Eudktyiim MaRöii. 



