EEPOET ON THE TETEACTINELLIDA. 
cxliii 
Family I. GEODiiDiE, Gray. 
Geodiadm, Gray, Proc. Zool. Soc. Lond., pp. 127, 492, 1867. 
Geodinidse, 0. Schmidt, Spong. Atlant. Gehiet., p. 68, 1870. 
Geodina, Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xvi. p. 66, 1875. 
Geodidae, Vosmaer, Bronn’s Klass. u. Ord. d. Thierreichs, Porifera, p. 315, 1887. 
History. — The earliest described Choristid Sponge {Cydonium muUeri, Fleming) 
belongs to this family; it was faithfully figured by Donati in 1750. The genus which 
has given its name to the family is Geodia, Lamarck, of which Lamarck described a 
single species, Geodia gihberosa.^ In his earliest work 0. Schmidt ^ included the genus 
Geodia with the Corticata, but when this group was dissolved a family Geodiadse was 
formed to receive the Geodine Sponges, this family and the Ancorinidse together including 
all the Choristid Sponges known to 0. Schmidt. Gray, however, had previously proposed 
a family Geodiadse which only differed from that of Schmidt by the exclusion of the 
genus Placospongia, Gray, for which a special family, the Placospongiadse, was instituted. 
Although Schmidt gives an account of Placospongia in his description of Atlantic 
Sponges, I do not think he can have had a very intimate acquaintance with it, or he would 
scarcely have laid so much stress on the supposed absence of trisenes in Caminus when 
the case was so much clearer in Placospongia, which is not only devoid of trisenes but of 
oxeas as well, these spicules being replaced by tylostyles ; perhaps a still more remarkable 
feature in this Sponge is the replacement of euasters by spirasters ; Gray being well 
aware of these facts, was fully justified in excluding Placospongia from the 
Geodiidse. 
Gray’s classification of the Sterrastrosa shows great insight and judgment. Omitting 
the definitions, which are not felicitous, it is as follows : — 
Family I. Geodiadse. 
Genus 1. Pachymatisma, Bwk. — Pachymatisma johnstonia, Bwk. 
2. Geodia, Lamk. — Geodia gihberosa, Lamk. 
3. Cydonium, Fleming — Gray wrongly quotes Cydonium barretti, 
Bwk. (which is o, Geodia), as an example, the type is Cydonium 
mulleri, Fleming. 
4. Erylus, Gray — Erylus mammillaris, 0. Schmidt. 
5. Triate, Gray — Triate discophora, 0. Schmidt. 
6. Caminus, 0. Schmidt — Caminus vulcani, 0. Schmidt. 
Family II. Placospongiadee. 
Genus 1. Placospongia, Gray — Placospongia melobesiodes, Gray. 
^ Lamarck, Mem. Mus. Hist. Nat. Paris, t. i. p. 333, 1815. 
^ 0. Schmidt, Spong. Adriat. Meeres, p. 49, 1862. 
