Absence of Basals in the Eugeniacrinidse. 333 



species which are known to science, and was surprised to find 

 that basals are present as usual, having about the same rela- 

 tive size as those of P. asteria. I cannot help suspecting, 

 therefore, that some of the other cases of the supposed absence 

 of basals in the Pentacrinidse may perhaps be due to errors of 

 observation. 



This, however, can hardly be the case in the Holopodidge ; 

 but there are other grounds for inferring that even in these 

 aberrant forms the composition of the calyx is perfectly normal. 

 First, as regards Holopus itself. Sir AVyville Thomson* 

 believed the cup to be formed by the first, and probably 

 also by the second radials, together with the basals ; and 

 the appearances presented by some sections of the lower 

 part of the cup, which had been made by him, certainly seem 

 to indicate the presence of the last-named plates. 

 • Passing to the allied, if not identical, genus Cyathidium, it 

 is difficult to determine any thing about the composition of the 

 I cup iii the Faxoe species j but Schliiter suspects the presence 



of basals in C. spileccense, and thinks he has seen traces of a 

 basi radial suture f. In the genus Cotylecrinus the radials 

 rest upon the upper edge of a hollow tube or cup which De 

 LoriolJ describes as a centrodorsal piece, since he has never 

 detected any trace of sutures in it. Its edge, however, is 

 marked by interradial ridges which separate the depressions 

 lodging the radials ; and Zittel§ has consequently suggested that 

 this part of the cup should be regarded as composed of anchy- 

 losed basals, a proposition to which I thoroughly assent. I 





would 



say the same, and for the same reason, respecting the 

 part of the so-called " support " in the recently esta- 



upper p 



blished genus Eadesicrinus , De Loriol 



A calyx much resembling that of the Holopodidge occurs in 

 the Palaeozoic Edrtocrtnus 9 the resemblance of which to Holopus 

 has been pointed out by Meek and Worthen. The lower part 

 of the cup is formed in young individuals by five distinct 

 I basal plates ; but when it approaches maturity and becomes 



1 free, " a calcareous deposit is secreted around the base, which 



I covers and obliterates the sutures between the plates "If. 



May we not suppose a very similar process to occur in the 



* " On the Structure and Relations of the Genus Holopus^ Proc. Roy. 

 Soc. Edinburgh, 1876-77, vol. ix. p. 407. 



t "Ueber einige astylide Crinoiden," Zeitschr. d. deutsch. geol. 



Gesellsch. Jahrg. 1878, p. 51. 



% Pal. Franf. /. c. pp. 188-192, pis. xix.-xxi. 

 § Palseontologie, p. 386. 

 II Pal. Fran$. /. c. pp. 99, 100, pi. xxix. 

 % Waehsmuth and Springer, u Revision of the Paheocrinoidea," Proc. 



Philad. Acad. 1879, p. 22. 





