Miscellaneous. 95 
to these segmental organs. In his so-called ‘Comparative Anatomy’ 
he speaks of the possibility of a comparison of the oviducts and 
tube to the segmental organs of the Vermes. This is completely 
refuted by the observations here given: the true segmental organs 
of the Vertebrata (hitherto detected only in the Selachia) have 
nothing to do with the tube and the oviduct ; the former originates 
from the primitive renal duct, and the latter is produced by a fold 
which finally leads to the formation of a tube; the tubs are only 
the permanently open orifices of the primitive renal groove, and 
they consequently originate in quite a different manner from the 
true segmental funnels. 
The comparison here made leads to far-reaching consequences. 
Assuming it to be correct, it follows that the Annelida are more 
nearly allied than the Ascidia to the Selachia, and therefore also to 
the Vertebrata in general (with the exception of Amphiovus). It 
might be objected that the spinal cord and the chorda are of more 
importance for the recognition of relationship than the primitive 
kidney and the segmentation of the body, so that the Ascidia are 
more nearly allied than the Vermes to the Vertebrata. But this 
objection is partly refuted by the circumstance that according to 
Kowalevsky’s investigations the ventral cord of the Vermes and 
Insecta is formed in a perfectly analogous manner to the dorsal cord 
of the Vertebrata. The chorda alone seems to offer any difficulty ; 
but it is still questionable whether the chorda of the Ascidia is 
really to be compared so unconditionally to that of the Verte- 
brata; and, on the other hand, Kowalevsky, in his ‘ Embryological 
Researches on Worms and Insects,’ even indicated as a chorda a 
fibrous cord discovered by Leydig in the earthworm and detected by 
Claparéde in numerous worms, and which in its origin and position 
between the ventral cord and the intestine exactly resembles the 
chorda of the Vertebrata. Nevertheless the histological structure of 
this cord is essentially different. 
If the embryo of an annelide be turned so that its ventral surface 
lies upwards, its section presents exactly the same arrangement of 
the organs as in the Selachian embryo. Consequently, by the dis- 
covery of the segmental organs, the belly of the annulose animal is 
identified with the back of the vertebrate. This is not the place to 
trace this conception to its further consequences ; in this respect, as 
also with regard to the detailed proof of the facts given above, 
reference must be made to a more complete memoir which will appear 
shortly in the second volume of the ‘Arbeiten aus dem zoologisch- 
zootomischen Institut in Wurzburg.’—Centralbl. fiir die med. Wis- 
sensch. 1874, No. 35. 
Wiirzburg, July 1874. 
Segmental Organs in adult Selachia. By C. Semper. 
IT can now follow up my former preliminary communication on 
the occurrence of segmental organs in Selachian embryos with a 
further statement that such organs may also be very easily detected 
even in adult animals, but only in fresh or very well-preserved 
