194 RITTER. [Vot. XII. 
That they did suppose the same conditions to hold for both 
genera is evident, although they say so rather indirectly. 
Thus, in summing up their results on the development of the 
heart “et de ses dependances chez la Claveline,’’ they say, p. 
317, “Chez la Claveline, comme chez la Pérophore, la vesicule 
interne du burgeon,” etc. ; and then follows a brief restatement 
of the relations between the primitive inner vesicle, the bran- 
chial and peribranchial sacs, the epicardium, the pericardium 
and heart, and the cloison, as they have been described in 
detail for C/avelina. In this connection I shall merely say 
that the description which they give for Clavelina does not 
apply in a single essential particular, excepting as to the forma- 
tion of the heart from the pericardium, to what actually takes 
place in Perophora. In describing the development of the 
heart I shall point out in detail the difference between the two. 
Pizon’s paper is entitled ‘ Histoire de la blastogénése chez 
les Botryllides,” and the author does not claim to have made 
so exhaustive a study of the numerous other genera which 
received his attention as he has of Botryllus and Botryllozds. 
As regards Perophora he seems to have examined it just enough 
to make himself feel safe in adopting the errors on this point, 
at least, into which Van Beneden et Julin had fallen. Thus, 
he says, p. 105, ‘‘Disons d’abord que chez des bourgeons 
a’ Amaroncium proliferum, de Circinalium concrescens (Giard), 
de Perophora Listert, de Clavelina Rissoane, je suis arrivé 
identiquement aux mémes résultats que Kowalevsky (Am. pro- 
liferum) et que Van Beneden et Julin (Clavelina Rissoana) a 
propos de lorigine du tube epicardique.” Then follows a 
brief description of the epicardium and its relation to the 
branchial sac and pericardium, which is the same as that already 
referred to as having been given by Van Beneden et Julin. 
But this writer’s statements on this point I shall also have to 
consider further after having described the development of the 
heart. 
= eee = 
a 6 oe 
Se ae 
