BATOCRINID&. A85 
at the outer surface. The pinnules form a longitudinal roll along the sides 
of each arm; they are closely packed, and their ends infold over the food 
grooves from the sides. In the fossil state the dorsal surfaces of the pin- 
nules are exposed to view, but in the living crinoid they evidently were 
capable of straightening out to expose their ventral surfaces, and to open the 
food groves of the arms to the water. ‘The pinnules are composed of very 
deep, elongate joints; they are contiguous at their proximal ends, and so 
regularly arranged that it appears as if they might have been connected 
laterally for a part of their length, only the upper parts being movable. In- 
terbrachials one; large; followed by two smaller ones, which meet with the 
plates of the disk. The anal plate rests upon two basals; it is nine-sided, and 
succeeded by three and two plates. Of the construction of the tegmen very 
little is known, it being generally concealed by the lower pinnules; but 
from appearances it was composed of large, subspinous orals, asymmetrically 
arranged, which alternated with five similar plates evidently representing 
radial dome plates. Anus excentric, opening directly through the disk. 
Column stout, circular. : 
Distribution. — Restricted to the Upper Silurian, and hitherto recognized 
only in Gotland, Sweden. 
Type of the genus: Barrandeocrinus sceptrum Angelin. 
Remarks. — Through the kindness of Dr. G. Lindstrém and the great skill 
and intelligence of Mr. Liljevall, we were enabled to procure a series of draw- 
ings made from specimens in the National Museum at Stockholm, by means 
of which the details of structure of this extraordinary Crinoid are shown very 
completely. (Plate VIII., Fig 1.) Although superficially presenting unique 
characters, it is a true Batocrinoid, and we find no necessity of recognizing 
for this genus a distinct family. The recumbent arm feature is found among 
the Hexacrinide, and also in one species of the Acrocrinide, in which it is 
as marked a character as in Barrandeocrinus, but in Acrocrinus and the other 
forms with recumbent arms — except Barrandeocrinus —the pinnules are 
stretched out, and their ventral surfaces are exposed instead of being folded 
over the ventral surface of the arm. 
Our generic description was made to agree with the Swedish form, and 
may have to be slightly modified should additional species be discovered 
hereafter. It is possible that the specimen figured and described by S. A. 
Miller in the 18th Report of the Indiana Geological Survey, p. 31, Plate 5, 
Figs. 13 and 14, under Cylicocrinus canaliculatus may belong to this genus. 
