| Popis: |
Salter, who was the first to introduce this Sponge to our notice, describes it as exhibiting a loosely reticulate skeleton, composed of large cruciform spicules, the rays of which lie all in one plane and cross each other at an angle of 80° He adds that the only sponge resembling it is his Amphispongia , which he regards as allied to Grantia —a view quite in accordance with his ideas in general on the Palaeozoic sponges, most of which he seems to have referred to the Calcispongia. In a foot-note he gives a quotation from a letter by Dr. Bowerbank, who, in equal accordance with his general opinions as to the affinities of fossil sponges, regarded Protospongia as allied to the recent horny sponge Spongionella , Bwbk., its orginally horny fibres having, according to him, been replaced by iron-pyrites. Hicks describes some spicular remains which he thinks may belong to Protospongia , and gives a diagrammatic figure of a fine specimen which he had discovered of Salter9s original species, P. fenestrata . Zittel places these Sponges with the Hexactinellidae, and in his group Dictyonina, which is nearly equivalent to Carter9s Vitreo-hexactinellidae . He further more closely defines its relations by placing it in the family Euretidae. Certainly the resemblance of the ordinary specimens of Protospongia to my Eubrochus clausus , also a member of the Euretidae, is very great, and at one time, long before the publication of Zittel9s monograph, led me to regard them as allied; fresh facts, however, have since shown me that this is not correct |
