XI. Balanocrinus. 4035 
SUMMARY AND CoNCLUSIONS. 
All the specimens from Biarritz to which d’Archiae and 
others have applied the name Pentacrinus didactylus belong 
to a single species. 
Examination of normal adult joint-faces shows that that 
species falls within the genus Balanocrinus as ordinarily 
understood. 
The specimens from the London Clay to which the names 
Pentacrinus subbasaltiformis and P. sowerbii have been 
applied, with the exception of a few fragments erroneously 
determined,-may be assembled in a series that falls within 
limits of variation no greater than those of B. didactylus, 
and in some respects even less, Therefore those specimens 
all belong to a single species. 
That species also belongs to Balanocrinus, though the 
characteristic features are less pronounced. 
The Biarritz species and the London Clay species are, 
however, distinct from one another, and must be known 
respectively by the names Balanocrinus didactylus V Archiac 
ex d’Orbigny, and Balanocrinus subbasaltiformis J. de C, 
Sowerby ex Miller. 
Sowerby’s figure 3 } (Brit. Mus. 57539), supposed by him 
to represent a cirrus of P. subbasaltiformis, is a stem of 
Isocrinus character with a pentagonal section actually visible 
in Sowerby’s engraving. It appears to be the stem of the 
later-described Cainocrinus tintinnabulum Forbes. 
Pentacrinus dixont Ooster, may be the same as Balano- 
crinus didactylus, but Ooster’s name must form the subject 
of a separate note. 
Pentacrinus diaboli Bayan, which Meneghini referred to 
B. didactylus as interpreted by him, is an alternicirrate 
Balanocrinus, with 2 & 3 facets to the whorl, but differs in 
its marked pentagonal section and other respects from 
d’Archiac’s species (Brit. Mus. E 22032-22052). 
Pentacrinus lorioli Noelli (1900, Atti Soc. Ital. Sci. Nat., 
XXxix. p. 28, pl. i. figs. 33, 34), based on cylindrical stem- 
fragments from the Upper Helvetian of Piedmont, was 
referred by me to Balanocrinus in the ‘ Zoological Record ’ 
for 1900 (1901), by reason of its joint-face, which Dr. Noelli 
himself compared with that of B. bronni. The “due in- 
fossature molto distinte” on what is presumably the 
hypozygal indicate that the stem was alternicirrate. 
Pentacrinus subbasaltiformis Miller, var. subrotundus 
De Gregorio (1894, Ann. Geol. et Pal., Livr. 13, p. 17, pl. ii. 
figs. 41, 42), from the Bartonian of Valrovina, may be 
