ae ie -“N " ee nM => : ———— = — ee Se See = 3 
a A NOE GUE eae Me eee Le Ee os 
— - a = = ———— = . - CPE es cacao prt cons Bean <= Ta hy a oe 2 — an 
ACTINOCRINID 2. 627 | . 
same order, which become free arm plates at the margin of the rim. The 
various series thus formed are in contact laterally, and united by suture with 
each other; those of adjoining rays, as well as those of the same ray, forming i 
together the peculiar rim which surrounds the calyx at the brachial zone. ! 
The plates of the rim are of nearly the same size; they form longitudinal, 
angular ridges, and from the outer end of each ridge proceeds an arm. Arm | 
openings large, all with a small respiratory pore at one side. Arms very 4 
numerous, moderately long, simple, closely crowded together, and rather | | 
small in proportion to the large size of the calyx. The pinnules, so far as 
observed, provided with well defined hooks. Interbrachials numerous, separ- 
ated from the interambulacral plates by the higher orders of brachials, 
generally from the palmars up. Interdistichals one or two. Ventral disk - os | 
convex, in form of a ten-rayed star, slightly plicated near the outer margins, | 
and composed of a large number of plates, which decrease in size outward. | 
The orals, although well defined in young specimens, can scarcely ever be 4 
identified in older ones. The inner floor of the tegmen is strengthened by 
braces, which increase in thickness as they recede from the centre, and on 
approaching the rim form tunneled passages for the reception of the ambu- 
lacra, The ambulacra follow the inner floor of the disk, being placed at | || 
a slight distance from it; they are roofed over wholly or in part by super- || 
imposed interambulacral pieces, which, together with the radial dome plates, | 
if present, form a rigid and independent covering above the food grooves. P| 
Column covered with rows of angular processes, passing up and down its 
sides at equal distances, giving to the column a highly sculptured, angular 
appearance, especially in its upper portions, where these processes are more | 
prominent, and in almost continuous vertical lines. They pass out from the 
nodal joints, but intrude upon the intervening smaller ones, and grow farther 
apart with the increase of internodal joints. 
Distribution. — This genus, like other extravagant forms, has a very | 
limited geological and geographical range, being restricted, so far as known, E 
to the Burlington group of the Mississippi Valley. 
Type of the genus: Teleiocrinus umbrosus Hall. 
ftemarks. — We have called Teleiocrinus “a modified and extravagant 
form of Cactocrinus”: nevertheless we regard it as a good genus. It is 
PP eee. 
evidently the lineal successor of that genus in the Upper Burlington lime- 
stone, having the same mode of bifurcation of the higher brachials, and other 
general similarities. Cactocrinus flourished abundantly in the Lower Burling- a 
