128 M. K. A. Zittel on Fossil Cahispongioe. 



Blastinia, Zittel. 



Achilleum p. p., Goldf. 



Actinospongia p. p., Pterosmila p.p., Pom. 



Astrosponyia p. p., Etal. 



Tetrasmila p. p., From. 



Sponge bud-like or clavate, simple, gradually narrowed 

 below into a peduncle. Vertex with radially converging, 

 more or less deep constrictions, which are continued over half 

 or more of the height of the sponge. The lower half is coated 

 with a wrinkled dermal layer ; the upper half naked, rough, 

 and porous. Skeleton consisting of vermiform interwoven 

 fibres. Central cavity, ostia, and canals wanting. 



This genus in many respects resembles Stellispongia, but 

 is easily distinguished by the want of an orifice furnished with 

 tubes in the vertex, and of a canal-system. 



Pomel refers the typical species (Achilleum costatum, Goldf.) 

 to Actinospongia, D'Orb. ; but in A. ornata, upon which 

 D'Orbigny had founded his genus, he remarks the presence 

 of " perforant proctides " both in the furrows and on the 

 eostEe of the vertex. According to these characters, Actino- 

 spongia, D'Orb., should be identical with Stellispongia. 



I believe also that Spongites alatus, Quenst., must be re- 

 ferred here, as the structure of several specimens from the 

 Blauthal exactly agrees with that of Achilleum costatum. 

 But whether Ceriopora alata, Goldf. (Taf. xi. fig. 8), is iden- 

 tical therewith, I regard as doubtful, notwithstanding the 

 external resemblance. The state of preservation of the silici- 

 fied specimens from Franconia permits no examination of the 

 microstructure ; and from the general habit I should regard 

 the small- winged bodies which Fromentel refers to the genus 

 Tetrasmila, and Pomel to Pterosmila, rather as Hydractinia3 

 or Bryozoa. Now that M. Steinmann * has demonstrated 

 that Thalamospongia at least belongs to the Hydractinias, the 

 whole family Porosmilinas of Pomel, with the genera Thala- 

 mospongia, D'Orb., Porosmila, From., Heterosmila, Pom., 

 Coelosmila, Pom., Pterosmila, Pom., and Cladosmila, Pom., 

 ought also probably to be removed to the same group. 



All the species are from the tipper Jura. 



1. Achilleum costatum, Goldf. Taf. xxxiv. fig. 7. 

 Spongites costatus, Quenst. Petr. cxxv. figs. 19-23. 



2. ? Actinospongia subcostata, Etal. Class, p. 150. 



3. Spongites alatus, Quenst. Petr. Taf. cxxv. figs. 24, 25. 



* Paleeontograpkica, xxv. 



