4 
front border of the periproct? The half formed surånal is not 
the relic of a pre-existing «disque central»: at least I know of no 
structure in pre-existing Echinoid genera to which such a term has 
been or could be applied. If it has any significance it is as 
showing the mode of origin of the permanent and fully formed 
sur-anal in the Saleniidae"). In itself it can hardly be the fore- 
runner of the Saleniid sur-anal", since Palæopedina cannot be 
regarded as an ancestor of the Salenids. I fully agree with Dr. Bather 
in this view of the origin of the suranal plate of the Salenids. 
To regard the suranal plate as a case of atavism — ,,0ne of those . 
cases of the sudden reappearance of an ancient structural feature 
after a long period of time" — as suggested by Agassiz (,,Blake" 
Echini p. 16) there is nothing to support. Likewise there are no 
facts to support a supposition that the suranal plate may have 
originated through a fusion of the anal plates, as seems to be 
expressed by the Sarasins when saying: ,,Die Analplatten der 
Saleniden haben also die Tendenz zu ver- 
schmelzen" (Uber die Anatomie der Echino- 
thuriden und die Phylogenie der Echino- 
dermen. Ergebn. naturw. Forschungen auf 
Ceylon. I. 1887—88, p. 150). 
Some words may here be said of the 
genus Gauthieria Lambert. The remar- 
kable apical system of this genus (Fig. 6) 
is described by Lambert?) (Op. cit. p. 4) Fig. 6. Apical system of 
i Te Gauthieria radiata. 
as consisting of «19 Une plaque centrale (Fro STER me 
hexagonale; 29 Trois plaques secondaires 
antérieures, hexagonales; 3? Des plaques suranales variées, au 
nombre probable de huit» — besides, of course, the usual number 
of genital and ocular plates. Lambert lays great stress on this 
central plate. «Cette plaque centrale hexagonale tout å fait par- 
1) The italics are mine, ; 
?) J. Lambert. Note sur un nouveau genre d'Echinide de la Craie 
de ''Yonne. Bull. Soc. sci. hist. & nat. de "Yonne. 1888. 
