M. K. A. Zittel on Fossil Hexactinellida. 515 



which reach only to the inner wide-meshed layer. On the 

 inner wall the mesh-openings serve as influent ostia. 



^ScT/pMa heteromorpha^ Reuss, Bohm. Kr. xviii. 1, 2 

 (non 3, 4). 



Family 9. CoeloptycMdse. 



CcELOPTYCHiUM, Goldf., see p. 419. 



Cceloptychium agaricoides^ Goldf., Zitt. Abhandl. k. bayr. 



Akad. ii. CI. Bd. xii. iii. p. 59. 

 C. deciminum^ Bom., Zitt. ibid. p. 62. 

 C. lobatum, Goldf., Zitt. ibid. p. 73. 



B. Lyssakina, Zitt. X. 



ACANTHOSPONGIA, M'Coy. 



Syn. Sil. Foss. Irel. p. 67 {Acanthaspongia) . 



The great axis of the spicules becomes 5-10 millims. long, 

 the other two are shorter. The crossing-nodes are thickened 

 and solid. The six arms become thinner towards the tip, and 

 swell towards the centre. Axial canals distinctly visible. 



'\Acanthospongia silurensis^ M'Coy, I. c. p. 67. 

 A. Simthii, Young, Nature, 1876, p. 481. 



Staukactinella, Zitt. 



Form of the sponge-body spherical, unstalked. Skeleton 

 consisting of large, simple, isolated sexradiates with arms of 

 unequal length. In general one ray is much elongated (6-8 

 millims. long). The spot at which the arms cross is scarcely 

 thickened ; and generally the arms are of the same thickness 

 throughout their whole length. 



Stauractinella jurassica^ Zitt. 



?Acestea, F. Rom. 



Fossile Fauna der Gescliiebe von Sadewitz, p. 56, t. vii. 7. 



The bacilliform bodies are possibly spicules from the root- 

 tuft of a Hexactinellid. 



Supplement. 



The foregoing Memoir was read on the 13 th of January 



X Possibly the genus Astrceospongia, Rom., is also to be referred as an 

 aberrant form to the Lyssakina, although the large stellate spicules, con- 

 sisting of calcspar, of this sponge possess three axes lying in the same 

 plane and besides these a perpendicular (but always rudimentary) axis, 



35* 



