A treatise on zoology . adult. Sacculi almost always present. (See structural details ofAniedon, Figs. IX., XV., XVIII. 2, 3, 4, XIX., XXX., XXXIII., XLVL,XLVIL, XLIX. 8, 9, LIV., LV.) Genera—TVwoW^enmnws, Etallon (1859),Jurassic and Cretaceous of Switzerland, France, and Portugal (Fig. CXVI I.);scarcely differs from Mesocriiuis, excej^t in the reduction of BB andpresence of a cirriferous centrodorsal at the top of the fairly stout stem ;our knowledge of this most important form is due to de Loriol, Theremaining Antedonidae retain the portion of stem below the centrodorsalonly in the brephic s
A treatise on zoology . adult. Sacculi almost always present. (See structural details ofAniedon, Figs. IX., XV., XVIII. 2, 3, 4, XIX., XXX., XXXIII., XLVL,XLVIL, XLIX. 8, 9, LIV., LV.) Genera—TVwoW^enmnws, Etallon (1859),Jurassic and Cretaceous of Switzerland, France, and Portugal (Fig. CXVI I.);scarcely differs from Mesocriiuis, excej^t in the reduction of BB andpresence of a cirriferous centrodorsal at the top of the fairly stout stem ;our knowledge of this most important form is due to de Loriol, Theremaining Antedonidae retain the portion of stem below the centrodorsalonly in the brephic stage, while their BB further diminish during geo-logical periods, their adcentral portions fusing into a small 10-rayed plate. Fio. CXVII. Thiolliericrinuif. 1, ,cup seen from helow, no basalsvisible (from Brit. Mas. 49222rt).2, T. liibeiroi, from the side,sliowing basals and facets forcirri (reconstructed from deLoriols figures). CD, centro-dorsal, still bearing facet (Sf)for attachment to stem, x the rosette, which lies above the chambered organ, and in some speciesof Antedon is all that remains of BB. There is also traceable in the armsa gradual attenuation and, in many cases, increase of forking, with apartial or entire loss of calcified covering-plates. Antedon, de Fremin-ville (1811 ; synn. ylZerfo, Leach ; Comatula, Lamarck, ^xtrs; Hibernula^Fleming ; Phytocrinus, de Blainville ; Solanocrinus, Goldfuss ; HyponomeyLoven ; Geocoma, Fraas non dOrb. ; et alia), Lias to Recent, almost all seas,littoral to 2900 fathoms. Arms fork once or more ; Amb usually present,especially on pinnules. The genus is divisible into 9 groups, differing inarm-structure and distribution. Eudiocrimis, P. H. Carp. (1882 ; , Semper non Salter), Neocomian (?) to Recent, Pacific and B. ofBiscay, 50 to 900 fathoms ; differs from Antedon only in non-forking ofarms. Promachocrinus, P. H. Carp. (1879), Pacific and South Sea, 70 to1800 fathoms; 10 RR, probably a persist
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