NORTH ZOOL. GAL.] NATURAL HISTORY. 
137 
The Class Crinoidea (Case 24) are furnished with five 
arms, having a series of processes on each side like a 
feather. The arms are generally forked at their base, and 
often repeatedly subdivided. Their body is surrounded 
with hard shelly plates. One recent genus, Comatulci , is 
free, but the other Pentacrinites and many of the fossil 
genera, as, Encrinites and Poteriocrmites , &c., have an 
elongated peduncle, which is furnished with claspers, like 
those on the back of the Comatula. 
The Class Sph&ronoida are only found fossil and like 
the former, but they have no arms, and the body is more 
or less spherical, with a large aperture closed by five 
valves on the side of the vertex, between it and the 
costals, and they are only marked with scattered pores. 
The class Blasteroida (Case 24) appear to be nearly 
allied to the Crinoidea , but they chiefly differ in having no 
arms, and in their body being marked with five double 
series of holes like the ambulacra of Sea Eggs, as the 
genera Pentremites and Orbitremites . They are only 
found in a fossil state. 
The following List will show 7 at one view the Arrange¬ 
ment of the Radiated Animals, and the Numbers indicate 
the Table Cases of this Room in which the genera in the 
collection are placed. 
Sub-kingdom. 
Centronix. 
Section I. 
Echinodermata. 
Class I. 
Ditremata. 
Order I. Echinida. 
Fam. 1. Cidaridce. 
Cidaris, Case 1 
Acrocidaris 
Pedina 
Tetragramma 
Acrosalenia 
Echinopsis 
Hemicidaris 
Diadema—1 
Astropyga 
Fam. 2. Echinidce. 
Cyphosoma 
Salentia—2 
Peltastes 
Goniopvgus 
Goniophorus 
Acropeltis 
Arbacia—2 
Echinus—2, 3, 4 
Hipponoe—4 
Echinometr a— 5 
Colobocentrus — 6 
H eterocentr u s—6 
Fam. 3. Scutellidce . 
Echinanthus — 7 
Lagana— 7 
Echinocvamus— 7 
Fibularia—7 
Echinarachnius—8 
Echinodiscus—8 
Encope 
Amphiope 
Heliophora 
Lobophora 
Fam. 4. Galeritidce. 
Echinolampas—9 
Conoclypeus 
Pygurus 
Cassidulus 
Amblypygus 
Clypeus 
Nucleolites 
Echinobrissus—9 
Catopygus 
Pygorhynchus 
Hvboclypeus 
Galerites—9 
Pyrina 
Globator 
Nucleopygus 
Pygaster 
Discoidea 
