Sjjonges fro7n the Atlantic Ocean. 479 



Fig. 42. Isodictya spinispiculum, spicule of. Scale l-21tli to 1-GOOOth 



inch. 

 Fiff. 43. Micructoiia intexfa : a, skeleton-spicule ; b, biliamate ; c, bihamates 



in the mass. Scale l-24th to l-(i()00th inch. 

 Fiff. 44. XatUhidium bicinatum. Scale l-12th to 1-UOOOth inch. 



Pl.-vte XVI. 



Fi(/. 45. Geodia nodastrella. a, '^ zone-spicule," viewed laterally ; b, end 

 view of head ; c, " body "' or lar^'e skeleton acerate spicule ; rf, 

 " anchoring'-spicule " fluked and forked ; e, body-stellate ; /, sili- 

 ceous balls of crust, globidar and elliptical forms ; r/, nodostellate 

 of dermis and crust; h, dermal acerate : all on the same scale, 

 viz. l-48tb to l-1800th inch, i, body-stellate, more magnified ; 

 Ji, nodostellate of dermis and crust, more magnified. 



Fi(/. 46. Geodia meyastreUa on a fragment of Curullides : a, sponge ; 

 b, aperture or common vent ; c, pore-areae ; (/, fragment of 

 Corallistes Bowerbcnikii. 



Fiff.4Q'. The same, spicules of. o, zone-spiciUe ; 6, less frequent form of 

 bead of zone-spicule; c, " lx)dy" or large skeleton acerate spicule ; 

 d, anchoring-spicules, fluked and forked ; e, megastrella, arms 

 microspined ; /, body-stellate ; ff, siliceous balls of crust, globular 

 and elliptical forms ; /(, dermal stellate ; i, dermal acerate : all 

 on the same scale, viz. l-48tli to l-1800th inch, k, megastrella, 

 more magnified ; /, body-stellate, more magnified ; m, dermal 

 stellate, more magnified. 



Fiff. 47. Geodiu tnegastrella, var. Iceiispina. a, zone-spicule ; b, body or 

 large skeleton acerate spicule ; c, anchoring-spicules, fluked and 

 forked respectively ; r/, megastrella ; e, siliceous balls of crust ; 

 /, stellate of dermis and crust ; (/, dermal acerate : all on the 

 same scale, viz. l-48th to l-1800th inch, h, megastrella, more 

 magnified; i, spines broken oil"; k, dermal stellate, more mag- 

 nified. 



Fig. 48. Tethga cranium, var. i/tfrequen.9. a, projecting forked anchoring- 

 spicule, with arms truncated and terminating in little cup-shaped 

 excavations with serrated margins respectively ; c, projecting 

 fluked or anchor-like anchoring-spicule : scale l-48th to l-UOOOth 

 inch, b, extremity of arm of forked form ( «), more magnified. 



Fig. 49. Tethya cranium, var. abgssorum : a, two bihaniates, magnified to 

 show that they are spinous. Scale 1-Cth to 1-GOOOth inch. 



Fig. 50. PuchcLitrella parasitica. «, radiate skeleton-spicule, showing that 

 its arms are thrice forked ; b, shaft, prolonged above as well as 

 below ; c, acerate skeleton-spicule ; d, spinous bacillary flesh- 

 spicule ; /, minute stellate : all on the same scale, viz. l-24tb 

 to l-(J000tli inch, e, spinous bacillary flesb-spicule, more mag- 

 nified. 



Fig. 51. Microciona minutnla : cr, large skeleton-spicule ; 6, diflferent forms 

 of its bead; c, slender acuate ; rf, bihamates. Scale l-24th to 

 1-GOOOth inch. 



Fig. 52. Corticium parasiticum, spicules of. Scale l-24th to l-6000th 

 inch. 



Fig. 53. Cometella simplex, natural size. 



