94 Miscellaneous. 
On the Relationship of the Vertebrata and Annelida. 
By C. Semper. 
It is well known that the Ascidia are regarded with Kupfer and 
Kowalevsky as the nearest relatives of the Vertebrata; and this 
opinion is supported by the analogous mode of production of the 
nerve-cord and the presence of a chorda between it and the intes- 
tine in both groups of animals. But it is forgotten that the Verte- 
brata are segmented animals, while the Ascidia are not so: the sole 
indication of a segmentation in the latter appears to lie in the oc- 
currence of spinal nerves in the tail and hinder part of the body of 
the larva of Asctdia mentula, as affirmed by Kupfer. 
This gap is now filled in a most unexpected manner by the dis- 
covery of segmental organs in Selachian embryos. In Acanthias, 
Centrina, and Scyllinm I have found funnel-shaped openings leading 
into ciliated ducts in connexion with the primitive kidneys; they 
are placed, one pair in each segment (metamere), right and left of 
the mesentery, along the whole of the body-cavity. They are pro- 
duced by depression of the peritoneal epithelium, and are only 
secondarily connected with the lateral canals of the primitive renal 
duct, which also issue segmentally. The funnels in Acanthias are 
very large ; and their cilia vibrate strongly. In Centrina and Acan- 
thias they may be detected by the lens even in nearly mature em- 
bryos; in Scylliwm, on the contrary, they disappear very early. 
In Acanthias the ovary is developed without any participation of 
the segmental organs; but in the male the seminal duct seems to 
become developed by a peculiar process of budding and amalga- 
mation of the segmental funnels. 
Except in a single point, the comparison to the segmental 
organ of an annelide may be completely carried out. In the one, as 
in the other, they are repeated in pairs in the segments of the body: 
they have a ciliated funnel opening freely into the cavity of the 
body ; the ciliated duct springing from this leads into a glandular 
segment (in the Vertebrates to the Malpighian body or primitive 
kidney); they are inintimate relation with the genital organs; and, 
lastly, they are produced in their glandular and infundibular portion 
from the mesoderm. The sole distinction consists In the mode of 
opening of these excretory organs: in the Annelida each seg- 
mental organ opens separately in the corresponding segment of the 
body ; in the Vertebrata they unite with the primitive renal duct, 
which in the Selachia, as in the Teleostea, is a product of the peri- 
toneal epithelium. This contradiction eannot, however, be used as 
an argument against the comparison of the two sets of organs, as 
the union of the glandular part with the efferent ducts is in both 
cases produced secondarily by the coalescence of the original separate 
rudiments ; moreover the so-called aquiferous vessels of the Rota- 
toria are universally compared to the segmental organs of the 
Vermes, although in the former, just as in the Vertebrata, two effer- 
ent ducts opening into the cloaca take up the secretion of the glands, 
which open by several funnels into the body-cavity. 
it might appear that a statement of Gegenbaur’s is to be referred 
