398 LEFEVRE. [Vor. XIV. 
observed the tube over the dorsal wall of the branchial sac, but 
did not obtain stages which were young enough to enable him 
to determine its origin. He concludes, however, on the insuff- 
cient evidence of Kowalewsky’s observations on Perophora, 
that the dorsal tube arises as a diverticulum of the endodermal 
wall. Since, in Clavelina, the later stages in the development 
of the dorsal tube are similar to those of Perophora, he holds 
that in this ascidian, also, the origin is the same. In two of the 
Polyclinidae, vzz., Amaroucitum proliferum and Circinalium, in 
Didemnum niveum andin Astellium spongiforme, he has observed 
the dorsal tube arising as an endodermal diverticulum, which 
acquires a secondary opening into the branchial sac at its 
anterior extremity, just as in Botryllus. In none of these. 
forms did he determine the origin of the ganglion, but he comes 
to the unwarranted conclusion that this structure is derived, 
independently of the dorsal tube, in the same way as he has 
described for the Botryllidae. 
Hjort (9) has recently studied the development of the neuro- 
hypophyseal system in the buds of Glossophorum sabulosum, 
one of the Polyclinidae, and Caullery (1) in Glossophorum 
luteum, Circinalium concrescens,and Diplosoma gelatinosum, and, 
although both of these authors find that the dorsal tube arises 
in the manner described by Pizon, that is, as an anteriorly 
directed endodermal diverticulum, they give a different account 
of the origin of the ganglion. In all the species studied the 
ganglion is formed as a differentiation of the dorsal wall of the 
hypophyseal tube, and has, therefore, a common rudiment with 
the latter. Their results are in agreement with what Hjort has 
found in Botryllus, except that in all of the above-mentioned 
ascidians the hypophysis lies below the ganglion, whereas in 
Botryllus it is above. 
Finally, Ritter (24), who has recently described the bud 
development of Goodsiria, a genus in which budding had not 
been observed before, finds a complete agreement, concerning 
the origin of the neuro-hypophyseal system, with Hjort’s work 
on Botryllus. 
In the same paper Ritter gives a preliminary account of 
some observations on the development of the buds of Perophora 
