I Absence of Basals in the Eugeniacrinidas. 331 



I planes in a fractured calyx*, is altogether worthless ; for t!ie 



I calyx in question consists of the ring of radials detached from 



I the top stem-joint (anch/losed basals, mihi). Neither does it 



I follow, as he asserts on p. 407, that if the " top stem-joint " 



I really consists of five anchylosed basals it would show five 



cleavage-planes, as is the case with the radials, and not three 

 only, as in a specimen figured by Quensteclt ; for if the 

 anchylosis had proceeded so far as to obliterate the interbasal 

 sutures, one might surely expect that the independence of their 

 I cleavage-planes would be also lost. 



I In certain species of JEugeniacrinus, and notably in E. 



\ nutans , the whole calyx is considerably inclined to one side, 



so that its axis makes a more or less open angle with that of 

 I the stem. In these individuals the u top stem-joint " is more 



! or less truncated obliquely. Quenstedt calls it the Halsband 



I or Halsstiick, and says that it u verengt sich auf einer 



Seite, kann sogar auf der concaven ganz verschwinden." 

 Among his numerous figures, illustrating the different modifica- 

 tions of form that this piece assumes, there is one which shows 

 nothing externally but a small knob immediately below the 

 interradial suture on the convex side of the calyx. All sorts 

 of gradations, however, can be traced between this condition 

 and that of a large and symmetrical " top stem-joint." What- 

 ever the one is, the other must certainly be of the same nature. 

 But I do not think that the existence of these variations is 

 any very serious objection to the view here advanced, that 

 the " top stem-joint really consists of a ring of united basals, 

 though I admit that the variations in symmetry are of a some- 

 what unusual character. Many Neocrinoids (e. g. Pentacrinus 

 decorus and Antedon scrobiculata) present considerable varia- 

 tions in the actual size of the basal plates ; but I cannot call 

 to mind any such variations of symmetry as are presented by 

 the basals of Eugeniaerinus nutans, except among certain 

 Palaeocrinoids and in the Astrocrinidae among the Blastoids ; 

 and even these do not furnish us with a very exact parallel. 

 Nevertheless I prefer to believe in the presence of these im- 

 portant elements of the calyx of a Crinoid, even though in a 

 modified form, rather than to regard them as absent alto- 

 gether. 



According to Mons. de Loriolf, Tetracrinus is distin- 









guished, among other characters, by " l'absence complete de 

 pieces basales, mais la presence, par contra, d'un article basal 

 semblable k celui des Apiocrinus, et faisant partie du calice." 

 I cannot help thinking that the name " article basal" is an 



Op. tit. p. 398, tab. lOo. tigs. 57-59. 

 t Pal. Fran?. /. c. p. 181. 



I 23* 



