XI. Balanocrinus. 397 
It seems probable that there was rarely a long succession 
of whorls with only two cirri, still less with only one, but 
that the succession was 2: 2:8. Considering the fairly 
large proportion of specimens with whorls of three in our 
material, it is strange that that number should not have 
been noted by previous writers. Dom Aurélien Valette, in 
his letter of 14 September, 1916, does, however, say ‘‘ deux 
ou trois tout au plus.” 
Quenstedt (1878, ‘ Encriniden,’ p. 268, pl. xcix. fig. 170) 
gave the name Pentacrinus tridactylus to a stem-fragment 
from Tertiary beds near Castellane in S. France because 
there were 3 cirrus-facets opposed at the node. This, how- 
ever, seems from the figure to be an Jsocrinus. 
The preceding facts fully bear out the anticipation of 
P. H. Carpenter in his description of Pentacrinus alterni- 
cirrus (1884, ‘Challenger Rep., Stalked Crinoids,’ pp. 822, 
323), which is referred by A. H. Clark to his Endoxocrinus. 
In that species there is a regular alternation of 2 with 3 curt 
to the whorl, as “ the leaves on the stem of a Labiate plant.” 
Only one irregularity was noted in the whole 147 nodes 
examined : in one stem the seventh and eighth nodes both 
bore 3 cirri in such a position that one cirrus fell on the 
same radius in both whorls. Carpenter mentioned the 
reduction of cirri to two in Pentacrinus bronni Hagenow 
(which is a Balanocrinus), and P. didactylus, and to three in 
P. tridactylus, and suggested that ‘if longer pieces of these 
stems were known they might show the same regular alter- 
nation in the positions of the successive cirrus-whorls which 
is so striking in Pentacrinus alternicirrus.” 
Neither in his published writings nor in his letters to me 
on this subject did Carpenter suggest any cause for this 
remarkable peculiarity, and the matter has since remained 
where he left it. 
We turn now to the similar specimens from the London 
Clay. Concerning them the main questions to be answered 
are: What is their generic position? Do they include more 
than one species? Are any or all of them conspecific with 
any of the foreign specimens? The answers to these 
questions are given in the following Synonymy :— 
Balanocrinus subbasaltiformis. 
“x d 58. Entrochus-Asteriae, from a Brick Clay-pit, on the South- 
side of Islington.” 
“x d 59, 60. Entrocho-Asteriae, found in the Tile Clay-pit behind 
Tr inity-Chapel, at the end of Bondstreet, St. James’s,” 
