THYSANOCRINID_E. 189 
Remarks. — We have changed the name Glyptasteride, which we pro- 
posed in 1885,* into Thysanocrinide, because we found it necessary to give 
up Hall’s genus Glyplaster. We also discard Dimerocrinus Phillips, and Lu- 
crinus Angelin, and arrange the species of both under Zhysanocrinus.t That 
Phillips’ figures of Dimerocrinus were insufficient for generic identification, is 
shown by the fact that the genus has been referred by Roemer and Dujardin 
Asa = 
Fic. 8. Lhysanocrinus. Fic. 9. Lampterocrinus. 
and Hupé to the Cyathocrinidx, while Zittel made it the type of a mono- 
eyclic family.  Glyplaster and Luerinus were placed by Zittel along with 
Lampterocrinus, Archeocrinus, and Glyptocrinus under the Glyptocrinids ; in 
which he was followed by S. A. Miller, who added Reteoerinus and Xenocrinus, 
but withdrew them again in 1889. Thysanocrinus was placed at first by both 
authors under the Rhodocrinidx, from which afterwards Miller removed it to 
the Glyptasteride. 
The Thysanocrinide have their closest affinities with the Rhodocrinide. 
Both are dicyclic, but in the Rhodocrinidx the interradials at all five sides 
are in contact with the basals, thus, as a general rule, completely isolating 
the radials laterally ; while in the Thysanocrinidx the radials are in contact 
all around except at the posterior side, where the anal plate overlies the 
basals. This bilateral symmetry in the arrangement of the plates of the 
dorsal cup is accompanied by a marked asymmetry in the general form of 
the calyx, and especially of the ventral disk, which is more or less enlarged 
* Revision, Part ITTI., p. 89. t See under Thysanocrinus. 
