LOWER HELDERBERG ROCKS. 
14? 
PLATES OF UNDETERMINED CRINOIDIAN OR CYSTIDIAN BODIES. 
Plate LXXXVIII. Pig. 5-9. 
The specimens are thickened, hexagonal or irregular plates, with margins in¬ 
dicating a suture-like junction with other plates or some other similar body : they 
have all a cicatrix upon the centre of the inner side. The surface aspect and texture 
do not differ from plates of Edriocrinus; but with our present knowledge of that 
fossil, these could only be referred conjecturally to the summit of the known species, 
or possibly are the free bases of a similar form. 
ADDENDA. 
Mariacrinns ramosus (n.s.). 
Plate II. Fig. 2 & 3. 
Body urnsliaped. Basal or pelvic plates small. Radial plates longer than 
wide. Arm-plates two, resting on the upper sloping edges of the third 
radial, producing a double series, which again bifurcate on the third 
brachial plate above, giving origin to two pairs of arms ; the two inner 
or adjoining arms similar, and the two outer arms similar to each other. 
The central pair of arms bifurcate irregularly at least three times above 
the separation; each branch above the last bifurcation being composed 
of a double series of wedgeform plates, and below these points of a 
simple series of quadrangular plates. The lateral arms remain simple. 
Tentacula round, apparently furnished with a second series of tentacles. 
Surface of plates marked by strong radiating ridges. 
This species presents another modification of the arm structure, intermediate to 
that of M. nobilissimus and that of M. piumosus. The lateral arms of each double 
pair, or those proceeding from each radial series, represent the auxiliary arms of 
M. nobilissimus , M. packydactylus , etc., while the central pair represent the large 
or principal arm of that species; the bifurcations being analogous to the armlets of 
those species. The modifications of structure affect only the arms : the body and 
base of arms are composed as in those species. 
Fig. 2. The specimen, natural size. 
Fig. 3. Diagram of structure, showing relations of radial series to arms, etc. 
Geological position and locality. Same as M. nobilissimus. 
