6 Dr. P. IT. 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 tlie student. The 

 German paleontologists have naturally followed Zittel, and 

 continue to s])cak of the dicyclic base as composed of para- 

 basals and infrabnsals, 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 

 tlic simpler name in all the remaining species of the genus. 

 This will be an endless source of confusion, and another is 

 afl'orded by Zittel 's own description of the calyx of Penta- 

 criniis. He states that it contains five basals, but adds that 

 five infrabasals are sometimes present. According to his 

 terminology, however, the species possessing them t should 

 have no basals, but parabasals ; but he gives no hint of this. 

 Then, again, Bury has recently demonstrated the ])resence 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 hoinologues in the 

 apparently monocyclic fossil Comatulce will retain their old 

 name. In these tliree 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 pro])Osed by Bather \. But in Zittel's teruiin- 

 ology the generic diagnosis will have to run somewhat as 

 follows : — " Calyx composed of radials and basals, or of radials, 

 ])arabasals, and infrabasals." Would it not be infinitely 

 simpler and less confusing to say '' 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 "subradials" was proposed in 1S54 by de 

 Koninck and Le Hon instead of parabasals, and was generally 

 adopted by the leading American ])ala3ontologists, e. g. Hall, 

 Billings, Meek and \Vorthen, and Whittiold. As long as 

 the homology of the plates so named with the basals of 

 monocyclic Crinoids remained unrecognized, this name was iu 



• ' PaltSontologie Francaise,' Terraiu .lurassiquo, tomo xi. pt. i. in\ 553, 

 660. 



t These species are uow refeiTod to Extracrhtus. 



\ "British Fossil Crinoids," Auu. & Mag. Nat. Ilist. ISW, ser. G, 

 vol. V. p. :iUi. 



