A treatise on zoology . hydrospires to the ambulacra. Moreover, in the con-struction of family names, these authors have contravened the laws ofnomenclature. The following classification attempts to overcome the above objectionswhile making as little change as possible :— Series A. Codonoblastida. Family 1. Codasteridae. Hydrospire- 92 THE BLASTOIDEA folds distinctly portions of the thecal plates, coming to the surface of theradial sinns. No distinct hydrospire-canal or pores ; spiracles developedimperfectly or not at all. Genera—Codaster, Phaenosdiisma^ CryptoschismayOrophocrinus. This family
A treatise on zoology . hydrospires to the ambulacra. Moreover, in the con-struction of family names, these authors have contravened the laws ofnomenclature. The following classification attempts to overcome the above objectionswhile making as little change as possible :— Series A. Codonoblastida. Family 1. Codasteridae. Hydrospire- 92 THE BLASTOIDEA folds distinctly portions of the thecal plates, coming to the surface of theradial sinns. No distinct hydrospire-canal or pores ; spiracles developedimperfectly or not at all. Genera—Codaster, Phaenosdiisma^ CryptoschismayOrophocrinus. This family coincides with that of Etheridge & 2. Pentremitidae. Hydrospire-folds, usually numerous, concen-trated at the lowest part of the radial sinus, and partly or wholly opens through spiracles bounded distally by convex. Ambulacra rather broad. Genera—Pentremitidea, Pentre-mites. This equals the Pentremitidae of Etheridge & Carpenter, Fio. XV. Thecas of typical 1, a Codonohlnstid—Pentremites robustus (from Brit. Mus. E8145).2, a Troostoblastid—TricoeZocrinMS woodmani (from Brit. Mus. E8171). 3 and 4, a Granato-hlastul—Orbitremites orbicularis (from the type-specimens, Brit. Mus. ES135). 3, from the , from below, with posterior interradius uppermost. All ligures nat. size. Series B. Troostoblastida. Family 1. Troostocrinidae. Elongateforms with linear ambulacra descending sharply outwards from the muchrestricted peristome. Hydrospire-folds only slightly concentrated, butcommunicate with exterior through pores, and througli spiracles boundedby A and lancet-plates. Genera—Troostocrinus, Metahlaslu,% equals the Troostohladidae of Etheridge & Carpenter. Family Elongate, stemless, asymmetrical, with four narrowambulacra, accompanied by unconcentrated hydrospires. Fifth ambula-crum shortened and widened. A minute. Genus—Ekutherocrinus. S
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
