58 I. IJIMA : HEXACTINELLIDA. I. 



Key to the Species or Euplectella. 



«• — Tlie parenchynml prlnoipalia of the circular ami longitudinal skeletal beams are staur- 

 actins. 

 a'. Spicules of the skeletal beams never in fusion. 



o". Parietal ledges well developed; oscularla of miscellaneous forms 



E. murshalli Ij. (Sagaml Sea; Suruga Gulf). 



b'. Parietal ledges little or not at all developed; oscularla mainly diactins. 



n'. Oxyhexaster with straight terminals, 50-70 [J. iu diameter 



-E oiceni Herkl. & Maesh. (NW. of Kyushyu). 



i'. Oxyhexaster with terminal rays bent near the outer end, 75-100 \i. in diameter. 



E. curvisldlala Ij. (S. of Kyushu). 



b^. Spicules of the skeletal beams in fusion, .at least in tjie basal region. 



(■'. Parietal ledges not developed; all meshes of the skeletal framework with a 



parietal oscnlum each; oxyhexaster not present 



E. fiimfkx F. E. ScH. (Sea of Bengal). 



d°. Parietal ledges or protuberances well developed ; a number of the meshes of the 

 skeletal framework without parictal^oscula ; oxyhexaster present. 

 c". Ledges cut up into irregular knobs, flaps, &c.; oscularia chiefly hexactins 



and pentactins E. imperialis Ij. (Sagami Sea; Suruga Gulf). 



d'. I^edges with tolerably sharp continuous edges. 



a*. Ledges low ; without graphiocome...£'. j-ejo/is F. E. Sen. (Sea of Bengal). 



6*. Ledges prominent ; with graphiocome...£'. a^pergiltum Ok. (Philippines). 



It. — Tiie parenchymal pi-incipalia of tlie circular and longitudinal skeletal beams are all or 



at least partially oxypentactins, or oxyhexactins with one ray directed distally and 



radially. 



c'. The parenchymal principalia are oxyhexactins witli a reduced proximal ray. 

 Stauractins may occur iu addition. 



I-. Distal ray of parenchymal oxyhexactins armed with prongs and conspicuously 

 projecting out of the external surface. Oxyhexaster with short slender principals 



and long terminals E. aspera F. E. ScH. (Indian Ocean). 



/-. Distal ray of parenchymal oxyhexactins smooth, not freely projecting (?) ; oxy- 

 hexaster with moderately long and thick principals and short terminals 



; E. crassiatellata F. E. Sen. (Mid-Pacific). 



d'. The parenchymal principalia are smooth oxypentactins with entirely suppressed 

 proximal rays. However, oxyhexactins may occur in addition. 

 g". Distal ray of parenchymal oxypentactins reaching to the external surface but 

 not beyond; yet, with outwardly projecting bundles of small thin diactins; no 



oxyliex.aster E. nodosa F. E. Sen. (Bermudas). 



/i". Distal ray of parenchym.al oxypentactins freely projecting out of the external 

 surface. 

 c'. Oxyhexaster represented by cl.asp-like or sigma-like fibnlte (oxydiaster) ; 



oscularia scepter-like mouactins E. jovis O. Schm. (AV. Lidies). 



/=■. Either typical oxyhexaster or onychaster present; no fibula'. 



c*. Body tubular, scarcely bellied; spicules nowhere in fusion; osculai-ia 



rough rod like diactins E. suberea AV. Tno.">fs. (Atlantic). 



rf*. Body distinctly bellied; spicules in fusion in certain parts; oscularia 

 unknown , F. ciu-uiner Ow. (Seychelles). 



