6 
Dr. P. H. Carpenter on the 
to one and the same set of plates, a method which, as it seems 
to me, is still more likely to confuse the student. The 
German palaeontologists have naturally followed Zittel, and 
continue to speak of the dicyclic base as composed of para- 
basals and infrabasals, a course which will not be made easier 
by some recent discoveries. Thus, for example, de Loriol 
has found infrabasals in two species of Millericrinus *, and 
the plates above them, hitherto called basals, must now be 
known as parabasals in these two species, though retaining 
the simpler name in all the remaining species of the genus. 
This will be an endless source of confusion, and another is 
afforded by Zittel ’s own description of the calyx of Penta - 
crinus. He states that it contains five basals, but adds that 
five infrabasals are sometimes present. According to his 
terminology, however, the species possessing them f should 
have no basals, but parabasals j but he gives no hint of this. 
Then, again, Bury has recently demonstrated the presence of 
infrabasals in Antedon rosacea ; so that in Zittel’s termin- 
ology the plates hitherto called basals in this type must now 
be known as parabasals, though their homologues in the 
apparently monocyclic fossil Comatulce will retain their old 
name. In these three genera therefore — Millericrinus , Penta - 
crinus (in the widest sense), and Antedon — some species are 
known to be dicyclic, while others are not, though the latter 
are in all probability only pseudomonocyclic, to use the con- 
venient term proposed by Bather But in Zittel’s termin- 
ology the generic diagnosis will have to run somewhat as 
follows : — u Calyx composed of radials and basals, or of radials, 
parabasals, and infrabasals.” Would it not be infinitely 
simpler and less confusing to say u Calyx composed of radials 
and basals, sometimes with the addition of infrabasals ” ? 
If this be admitted, it is clear that the same principle may be 
extended to definitions of families and larger groups, and the 
misleading term parabasals will then have to be finally 
abandoned. 
The term C( subradials ” was proposed in 1854 by de 
Koninck and Le Hon instead of parabasals, and was generally 
adopted by the leading American palaeontologists, e. g , Hall, 
Billings, Meek and Worthen, and Whitfield. As long as 
the homology of the plates so named with the basals of 
monocyclic Crinoids remained unrecognized, this name was in 
* * Pal^ontologie Fran^aise/ Terrain Jurassique, tome xi. pt. i. pp. 553, 
566. 
t These species are now referred to Extracrinus. 
j “British Fossil Crinoids,” Ann, & Mag. Nat. Hist. 1S90, ser. 6, 
yol. v. p. 316. 
