40 
the other anal plates, wliich leads to the conclusion that the „sur- 
anal“ plate of Salenia is only one of the anal plates which has 
been specially developed on account of the anal opening having 
moved to the posterior edge of the anal area, and even encroached 
upon the posterior genital plate, tending thus towards becoming 
exocyclic. This suggestion is very 
much strengthened through the ob¬ 
servations of Lambert on the genus 
Palæopedina x ). In this genus the 
periproct is „rejeté en arriére par 
une suranale plus ou moins persi¬ 
stante” (Fig. 5). In P. globulus (Ag.) 
„le plus souvent la position de la 
suranale est nettement indiquée par 
les contours antérieurement anguleux 
du périprocte; cependant chez certains 
individus la suranale a été moins 
développée et elle s’est pour ainsi dire confondue avec les plaques 
anales dans le cadre irréguliérement circulaire du périprocte. Il 
semble done qu’å l’époque lointaine de l’Hettangien la suranale plus 
variable n’avait encore acquis la fixité et l’importance qu’elle devait 
plus tard atteindre dans les Acrosaléniens et les Saléniens”. (Op. 
cit. p. 26—27). 
Bat her (Triassic Echinoderms of Bakony. 1909, p. 106) 
modifies this view in so far as he is not inelined to agree that 
Palæopedina has „a form of apex in which the more or less pro- 
longed persistence of the central disc has shifted the periproct to 
the rear“. „Is it not nearer the truth to say that the passage 
of the periproct to the rear has involved partial resorption of the 
posterior genital, while leaving a space to be filled by the inerease 
in size of a periproctal or anal plate, which comes into contact 
with the growing anterior genitals and so produces angles in the 
M J. Lambert. Etude sur quelques Echinides de IIufra-Lias et du 
Lias. Buli. Soc. sc. hist. et nat. de lYonne. 1899, p. 22. 
Fig. 5. Apical system of Pa¬ 
læopedina globulus (Ag.). 
Slightly restored at the mark. 
(From Lambert). 
