Silttric Cysioidca and Camarocrinus. — Schuchert. 231 
present. Plate 19 of other genera not developed. Anal area 
small but conspicuous and protruding, consisting only of the 
pyramid of six pieces. The prominence of the anal area is due 
to the protrusion of the bounding thecal plates of which there 
are four, or plates 7, 8, 13 and 14. One basal and two upper 
very small, discreet pectinirhombs. The„parts on plates 1, 12 
and 14 as a rule do not show the dichopores as these are deeply 
situated each in a pit with a high margin. Dichopores few. 
Ambulacra normally four in number. These are R I, R V, 
R IV, and R II. In rare cases either R I or R II may be ab- 
sent, or R V may be forked. Ambulacra depressed, more or less 
deeply excavated and, in normal individuals, continuing to or 
near to the column. Brachioles moderately abundant, short and 
stout. 
Column comparatively stout. Length unknown. 
Genotype, /. hartleyi, n. sp. 
The genus is named for Doctor Otto Jaekel of the Geolog- 
ical Institute of the Friedrich-Wilhelms University, Berlin, 
Germany, in recognition of the great service he has rendered 
paleontology by the very detailed description of the "Thecoidea 
und Cystoidea" forming volume I of his great contemplated 
work on the "Stammesgeschichte der Pelmatozoen." 
Jaekelocystis hartleyi n. sp. 
Length of a full grown theca 15 mm., width and depth 
about 11 mm. 
Ambulacra narrow, excavated into and but slightly elevated 
above the theca, and extending, in normal specimens, to the 
column. Each pair of ambulacra, or R I and R II, or R IV 
and R V, converging and almost touching each other near the 
column. In one individual R I is but half the normal length 
and R II is almost aborted, having but six brachioles. In an- 
other individual R I is entirely undeveloped while in a third 
specimen the absent one is R II. In a fourth specimen R A* is 
forked, the branch developing on the left. In full grown spec- 
imens there are about thirty-four brachioles to each ambulac- 
rum, seventeen on either side. Brachioles stout and folded 
over each other medially ; length unknown but apparently quite 
short. Ambulacral grooves narrow and shallow with very 
minute ambulacralia. 
