278 Scientific Intelligence. > 
peculiar forms in both, is the genus Edriocrinus (Hall)—“a crinoid which 
is sessile in its young state and firmly attached to other bodies by the 
base of its cup, but becomes free as it advances and gradually loses all 
evidence of a cicatrix; the base becoming rounded and smooth, or very 
rarely siren a depression or pit near the centre, which marks the 
original point of attachment. 
The following is a list of the genera and number of species of Crinoidea 
and Cystidea in the Clinton and Niagara groups, and the Lower Helder- 
_ berg and Oriskany Sandstone. 
1. Clinton and Niagara groups.—Closterocrinus 1, Glyptocrinus? 1, 
Homocrinus 2, Gispies aster 1, Thysanocrinus 4, Dendrocrinus 1, Ichthyo- | 
erinus 1 (+ 17), Lyriocrinus 1, Lecanocrinus 4, Saecocrinus 1, Mae 3 
stylocrinus 1, Eucalyptocrinus 3, Stephanocrinus 2, Caryocrinus 1, Melo- | 
eg Hleteroeystites 1, Callocystites 1, Apiocystites 1, Hemicystites : 
1; Pale 
2, ae. "dolderberg Group and Oriskany Sandstone —Homocrinu 
1, Mariacrinus 8, Platycrinus 4 (the first occurrence of this een 
Aspidocrinus 9, Edriocrinus 2, Brachiocrinus 1, Coronocrinus 15 nomalo- 
oe 1, Sphzerocystites 1, Apiocystites (=Lepadocrinus) Lae | 
eh . 
The new genera are: . 
Marracrrnus,—the Astrocrinites of Conrad but not of other Authors 
or pelvic plates four, Radial plates three in five series (3X5). 
Interradial plates three or more. Anal plates numerous. Brachia | plates 
two resting on each third radial; beyond this point the structure ditfers 
in different pad Sa of plates marked by elevated radiating 
strie or ridges which re or less prominent, or by nodes or short 
~aees a = varying in structure in different species. Resembles most 
RACHTOCRINUS.— Body unknown or none. Arms composed of numer 
ous articulations arranged i in single consecutive series (or of pentagonal 
joints in double series?). Base of arm rounded, without articulating s°_ 
. Tentacula composed of thickened node-like joints. 
__ Epriocrinvs. —Body subconical. Base solid, without division into 
“Plates: upper margin marked by six angles, with depressions between 10F — 
Insertion of radial plates. Radial plates five, eee in the five lar 
depressions on the med edge of the calyx. Ana | plates two, the 
one inserted in the smaller of the six impressions on the upper ™ 
the calyx; the second anal plate placed ke the upper edge © of t 
Brachial plates merous, consisting of thin Pal in coneesty 
“a gpm = broadly circular, depressed hemispherie ye : 
telliform : upper margins plain or plicate exteriorly ; the articulatin 
edges irregular. Radial plates and arms unknown. Point of at bases 
for column distinct, small. The specimens are broad scutelliform 
of Crinoids, sometimes near hemispherical. 
i aes 
: i 
% 2 
sf 
